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Miniaturized spectrometers have significantly advanced real-time analytical capabilities in fields such as environmental monitoring, healthcare diagnostics, and industrial quality control by enabling precise on-site spectral analysis. However, achieving high sensitivity and spectral resolution within compact devices remains a significant challenge, particularly when detecting low-concentration analytes or subtle spectral variations critical for chemical and molecular analysis. This study introduces an innovative approach employing guided-mode resonance filters (GMRFs) to address these limitations. Functioning similarly to notch filters, GMRFs selectively block specific spectral bands while allowing others to pass, maximizing energy extraction from incident light and enhancing spectral encoding. Our design incorporates narrow band-stop filters, which are essential for accurate spectrum reconstruction, resulting in improved resolution and sensitivity. Our spectrometer delivers a spectral resolution of 0.8 nm over a range of 370–810 nm. It achieves sensitivity values that are more than ten times greater than those of conventional grating spectrometers during fluorescence spectroscopy of mouse jejunum. This enhanced sensitivity and resolution are particularly beneficial for chemical and biological applications, facilitating the detection of trace analytes in complex matrices. Furthermore, the spectrometer's compatibility with complementary metal oxide semiconductor (CMOS) technology enables scalable and cost-effective production, fostering broader adoption in chemical analysis, materials science, and biomedical research. This study underscores the transformative potential of the GMRF-based spectrometer as an innovative tool for advancing chemical and interdisciplinary analytical applications. [ABSTRACT FROM AUTHOR]

A suite of diagnostics used to assess impurity content and dynamics has been updated, upgraded, and installed on the Pegasus-III Experiment. Typical plasma parameters during local helicity injection start-up are τshot ∼ 10 ms, ne ∼ 1 × 1019 m−3, and Te ∼ 50 eV. The deployed diagnostics are compatible with this modest temperature and density regime and provide species identification, source localization, and estimation of radiation losses. Impurity species are determined by recording time-evolving, single line-of-sight spectra at 1.25 kfps using a SPRED (Survey, Poor Resolution, Extended Domain) vacuum ultraviolet spectrometer. SPRED is equipped with 450 g/mm grating, giving a spectral resolution of 0.33 nm and a spectral range from ∼10 to 110 nm, useful to identify light impurity species in this temperature and density range. An absolutely calibrated spectrometer that collects light from the plasma at Rtan = 15.9 cm and Δt ≥ 2 ms is used as a visible survey spectrometer and for continuum measurements. The radiated power from the plasma is estimated with a photodiode-based diagnostic. Two 16-channel absolute extreme ultraviolet diode arrays are placed behind pinhole apertures, resulting in 32 lines of sight at Z = 0, with a spatial resolution of 2–3 cm and a time response of 60 kHz. A photometrically calibrated collinear Dα/near infrared filtered photodiode-based system measures the Dα emission and around 1040 nm. All these instruments have been designed to suppress electromagnetic interference from megawatt-class switching power supplies. [ABSTRACT FROM AUTHOR]

The first mirror is the front-end optic component that reflects light emitted from the plasma to the diagnostic system in fusion plasmas. Silicon carbide (SiC), known for its relatively high mechanical strength and radiation tolerance, has been selected as the substrate material for the first mirror in the ITER divertor vacuum ultraviolet (VUV) spectrometer. To measure the reflectivity of the ellipse cylindrical SiC mirror to be manufactured, a device for reflectivity measurement in the VUV wavelength range was developed. First, the reflectivity of a sample SiC mirror (15 mm diameter × 10 mm thick) was measured across the ITER-required incidence angles, and the results are reported in this study. A hollow cathode lamp with helium gas was used as the VUV light source in the wavelength range of 23–60 nm, and a dedicated VUV spectrometer to select specific wavelengths was developed. The spectrometer utilized laminar-type replica diffraction gratings (Shimadzu 30-006) and two back-illuminated charge-coupled devices (BI-CCD, Andor DO 940P-BEN) for the grating and detector, respectively. A cropping technique with aperture was employed to precisely localize the VUV light's reflection onto the SiC mirror surface. The experimentally measured reflectivity values of SiC at the required incidence angles of VUV light were compared with theoretically calculated reflectivity curves. The oxidation layer (SiO2) formed on the SiC surface and the incidence angle of VUV light to the BI-CCD chip (E2V) would be the factors affecting the accuracy of the reflectivity. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cell (DSSC) is a third-generation solar cell that can utilize natural dyes from leaves extract to absorb sunlight and generate electricity. This study aimed to investigate the performance of DSSC utilizing the leaf extracts of cassava, guava, and mango as a natural dye in terms of UV-Vis absorption and energy output. The experimental method was applied wherein the researcher constructed three DSSCs, each treatment applied the same fabrication, and construction. The UV-Vis Spectrum peak value and UV absorption was obtained from UV-Vis Analysis. The multimeter was used to record each voltage to determine the energy output produced by the DSSCs and the commercial solar cell. One-way ANOVA Analysis was used to determine the significant difference in UV absorption of natural dyes. In getting the significant difference between the three treatments and control in pairwise comparison in terms of energy output, One-Way ANOVA Analysis and Post Hoc Tukey were utilized. Based on the data result, there was no significant difference in UV absorption among the three natural dyes. This signified that the same pigment content gave almost the same UV absorbance at common UV Spectrum peak value in wavelength. The DSSC with natural dyes produced a smaller amount of electrical energy compared to commercial solar cells. There was a significant difference in energy output between the three treatments and the control. DSSCs utilizing natural dyes proved to produce electrical energy even in smaller amounts. [ABSTRACT FROM AUTHOR]

The Emirates Mars Ultraviolet Spectrometer (EMUS), aboard the Emirates Mars Mission (EMM), has been conducting observations of ultraviolet emissions within the Martian exosphere. Taking advantage of the distinctive orbit of the EMM around Mars, EMUS utilizes a dedicated strafe observation strategy to scan the illuminated Martian exosphere at tangential altitudes ranging from 130 to over 20,000 km. To distinguish between emissions of Martian origin and those from the interplanetary background, EMUS conducts specialized background observations by looking away from the planet. This approach has allowed us to investigate the radial and seasonal variations in Martian coronal emission features at H Lyman‐α, β and γ wavelengths. Our analysis supports the previous studies indicating that Martian exospheric hydrogen Lyman emission brightness attains its highest levels around the southern summer solstice and reaches its lowest levels when Mars is near aphelion. Additionally, a secondary peak emission at all altitudes is observed after perihelion during Martian Year (MY) 36, which can be attributed to a Class C dust storm. Our study establishes a strong correlation between solar flux and coronal brightness for these emissions, highlighting the impact of solar activity on the visibility of Martian corona. In addition, we have examined interannual variability and found that emission intensities in MY 37 surpassed those in MY 36, primarily due to increased solar activity. These observations help to understand potential seasonal patterns of exospheric hydrogen, which is driven by underlying mechanisms in the lower atmosphere and solar activity, eventually suggesting an impact on water loss in the Martian atmosphere. Plain Language Summary: Atomic hydrogen primarily forms as a product when Martian water undergoes various photochemical reactions. These hydrogen atoms encircle Mars and become illuminated by solar radiation, leading to the creation of Martian hydrogen corona. The Emirates Mars Ultraviolet Spectrometer (EMUS), on the Emirates Mars Mission spacecraft, is currently studying the Martian atmosphere using the ultraviolet light emissions of different atoms and molecules on Mars. In this study, we have analyzed EMUS observations and determined that atomic hydrogen emission intensities increase during the Martian southern summer and decrease as Mars moves farther away from the Sun. Furthermore, we have compared the hydrogen brightness between two consecutive Martian years and have found that the hydrogen brightness is higher in the most recent year primarily due to increased solar radiation. These observations help us understand possible patterns that occur during different seasons on Mars and the mechanisms underlying water loss in the Martian atmosphere. Key Points: We present the variability in Martian atomic hydrogen brightness from early Martian year (MY) 36 to the first quarter of MY 37Martian exospheric H Ly‐β and γ emissions reach their peak brightness during the southern summer of MY 36Martian corona is much brighter at H Ly‐β wavelength in MY 37 compared to the previous year due to increased solar irradiance [ABSTRACT FROM AUTHOR]

Quantifying the global bromine monoxide (BrO) budget is essential to understand ozone chemistry better. In particular, the tropospheric BrO budget has not been well characterized. Here, we retrieve nearly a decade (February 2012–July 2021) of stratospheric and tropospheric BrO vertical columns from the Ozone Mapping and Profiling Suite Nadir Mapper (OMPS-NM) on board the Suomi National Polar-orbiting Partnership (Suomi-NPP) satellite. In quantifying tropospheric BrO enhancements from total slant columns, the key aspects involve segregating them from stratospheric enhancements and applying appropriate air mass factors. To address this concern and improve upon the existing methods, our study proposes an approach that applies distinct BrO vertical profiles based on the presence or absence of tropospheric BrO enhancement at each pixel, identifying it dynamically using a satellite-derived stratospheric-ozone–BrO relationship. We demonstrate good agreement for both stratosphere (r = 0.81–0.83) and troposphere (r = 0.50–0.70) by comparing monthly mean BrO vertical columns from OMPS-NM with ground-based observations from three stations (Lauder, Utqiaġvik, and Harestua). Although algorithm performance is primarily assessed at high latitudes, the OMPS-NM BrO retrievals successfully capture tropospheric enhancements not only in polar regions but also in extrapolar areas, such as the Rann of Kutch and the Great Salt Lake. We also estimate random uncertainties in the retrievals pixel by pixel, which can assist in quantitative applications of the OMPS-NM BrO dataset. Our BrO retrieval algorithm is designed for cross-sensor applications and can be adapted to other space-borne ultraviolet spectrometers, contributing to the creation of continuous long-term satellite BrO observation records. [ABSTRACT FROM AUTHOR]

The spectroscopic detection of SO2 and unknown UV absorber substance in the H2SO4 cloud layer of Venus' atmosphere is currently a focal point in the study of the habitability of Venusian atmospheric clouds. This paper addresses the simultaneous detection requirements of multiple substances in the ultraviolet range of Venus' atmosphere and proposes a multi-channel hyperspectral imaging system design using pupil separation prisms and grating multilevel spectra. The system achieves a multi-channel design by splitting the entrance pupil of the telescope using prisms. Spectra from different channels are diffracted to the same detector through different orders of the grating. The system features a single spectrometer and detector, enabling simultaneous detection of spectra from different channels. It also boasts advantages such as compact size, ultra-high spectral resolution, and simultaneous multi-channel detection. The system design results indicate that within the working spectral range of three channels, the spectral resolution is better than 0.15 nm, surpassing previous in-orbit or current in-orbit planetary atmospheric detection spectrometers. With a Nyquist frequency of 56 lp/mm, the full-field MTF exceeds 0.7. The system's smile is less than 0.05 μm, and the keystone is less than 0.04 μm, meeting the requirements for imaging quality. [ABSTRACT FROM AUTHOR]

Spectral measurements play a vital role in understanding laser–plasma interactions. The ability to accurately measure the spectrum of radiation sources is crucial for unraveling the underlying physics. In this article, we introduce a novel approach that significantly enhances the efficiency of binary sinusoidal transmission grating spectrometers. The grating was tailored especially for Extreme Ultraviolet (EUV) measurements. The new design, High Contrast Sinusoidal Transmission Grating (HCSTG), not only suppresses high diffraction orders and retains the advantageous properties of previous designs but also exhibits a fourfold improvement in first-order efficiency. In addition, the HCSTG offers exceptional purity in the first order due to effectively eliminating half-order contributions from the diffraction pattern. The HCSTG spectrometer was employed to measure the emission of laser-produced Sn plasma in the 1–50 nm spectral range, achieving a spectral resolution of λ/Δλ = 60. We provide a comprehensive analysis comparing the diffraction patterns of different STGs, highlighting the advantages offered by the HCSTG design. This novel, efficiency-enhanced HCSTG spectrometer opens up new possibilities for accurate and sensitive EUV spectral measurements. [ABSTRACT FROM AUTHOR]

We present the first observations of the dayside coronal oxygen emission in far ultraviolet (FUV) measured by the Emirates Mars Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission (EMM). The high sensitivity of EMUS is providing an opportunity to observe the tenuous oxygen corona in FUV, which is otherwise difficult to observe. Oxygen resonance fluorescence emission at 130.4 nm provides a measurement of the upper atmospheric and exospheric oxygen. More than 500 oxygen corona profiles are constructed using the long–exposure time cross–exospheric mode (OS4) of EMUS observations. These profiles range from ∼200 km altitude up to several Mars radii (>6 RM) across all seasons and for two Mars years. Our analysis shows that OI 130.4 nm is highly correlated with solar irradiance (solar photoionizing and 130.4 nm illuminating irradiances) as well as changes in the Sun–Mars distance. The prominent short term periodicity in oxygen corona brightness is consistent with the solar rotation period (quasi–27–day). A comparison between the perihelion seasons of Mars Year (MY) 36 and MY 37 shows interannual variability with enhanced emission intensities during MY 37, due to the rise of Solar Cycle 25. These observations show a highly variable oxygen corona, which has significant implications on constraining the photochemical escape of atomic oxygen from Mars. Plain Language Summary: The highly sensitive Emirates Mars Ultraviolet Spectrometer (EMUS) onboard Emirates Mars Mission (EMM) is capable of observing ultraviolet emissions emanating from Mars. Oxygen in the Martian exosphere is hard to see because it's tenuous. In this study, the analysis of long exposure time EMUS optical observations show that the hot oxygen corona on Mars has a short term variability due to solar rotation. Hot oxygen corona also shows a long–term variability that depends on the Sun–Mars distance and the solar cycle progression. When comparing data from two Martian years, it is noticed that the oxygen corona became brighter when the Sun is more active. Key Points: Brighter O corona is observed during perihelion and dimmer during aphelion, indicating a strong relationship with the Sun‐Mars distanceThe variation in OI 130.4 nm brightness shows a linear correlation with solar EUV irradiance, with a short‐term solar rotation periodicityInterannual variability is observed from MY 36 to MY 37, showing an enhancement in O corona brightness with the rise of Solar Cycle 25 [ABSTRACT FROM AUTHOR]

A novel ultraviolet spectrometer has been developed and tested over 10 years at Lauder, New Zealand. The system, UV2, makes alternating measurements of the global and direct UV irradiance and can therefore be used to measure ozone and aerosol optical depth. After an analysis of the stability of UV2, these measurements, along with UV irradiance, are compared to relevant observations made by an additional UV spectrometer (UV4), a Dobson spectrophotometer (no. 072), and two radiometers measuring aerosol optical depth – a Prede sky radiometer and a Middleton Solar radiometer (SP02). UV2 irradiance is shown to be lower than UV4 by between 2.5 % and 3.5 %, with a standard deviation of a similar magnitude. Total column ozone values are shown to agree with Dobson spectrophotometer values with a mean bias of 2.57 Dobson units (DU) and standard deviation of 1.15 DU when using the direct sun measurements. Aerosol optical depth at 400–412 and 500 nm agrees to within 0.015 and is comparable to the difference between the reference radiometers. Further work is needed, particularly in the radiometric calibration at longer wavelengths, in order to determine if this instrument can supersede or enhance measurements made by the Dobson spectrophotometer or the aerosol radiometers. [ABSTRACT FROM AUTHOR]

A universal strategy for a rapid colorimetric method for Hg2+ in an aqueous solution is described. The specific binding of Hg2+ (thymine-Hg2+-thymine) with thiolated DNA-functionalized gold nanoparticles (AuNPs) via Au–S bonds increases the spatial hindrance of the AuNP surface, resulting in a weakened catalytic ability of AuNPs to catalyze the reaction between p-nitrophenol and NaBH4. Therefore, the color change time (CCT) of the solution from yellow to colorless becomes longer. Based on the kinetic curve of absorbance over time measured by a UV spectrometer, the level of Hg2+ in aqueous solutions can be easily quantified. A linear relationship between CCT and Hg2+ concentration was obtained in the 10–600-nM range with a detection limit of 0.20 nM, which is much lower than the limit value (10 nM) defined by the US Environmental Protection Agency for Hg2+ in drinking water. The excellent sensitivity comes from CCT as the signal output of the probe, rather than the absorbance or wavelength change used in traditional colorimetric probes as the signal output. [ABSTRACT FROM AUTHOR]

BepiColombo, the ESA/JAXA joint mission performed its first flyby of Mercury on 1 October 2021 and its second on 23 June 2022. PHEBUS observed the exosphere of Mercury during these flybys notably with its visible channels c404 (centered on the potassium emission line at 404 nm) and c422 (centered on the calcium emission line at 422 nm). The c422 signal shows not only an enhancement of calcium (Ca) near the dawn region but also a very extensive Ca exosphere on the morning side beyond 10,000 km. The e‐folding distance deduced from our Ca profiles (2,500–2,800 km) is in agreement with the value reported by MESSENGER at similar true anomaly angles. We use a Chamberlain model to determine the temperature and density at the exobase. Using the morning side low‐altitude data, we derived a high temperature at the exobase (>50,000 K), in agreement with the MESSENGER results. We also report a day/night asymmetry in the Ca exosphere that could indicate that the source of Ca is predominantly on the dayside or be the consequence of a shift of the main source of Ca away from the dawn region. The c404 channel detected additional species at low altitudes on the morning side during both flybys. Comparison with previous studies is inconclusive and further analysis will be necessary to identify the species. Nevertheless, we can note that the e‐folding distance deduced from our profile is relatively small (135 km) and that the Chamberlain model applied to our profiles seems to indicate a temperature at the exobase <3,000 K. Plain Language Summary: BepiColombo, the ESA/JAXA joint mission on its way to Mercury, has already flown over the planet twice in October 2021 and June 2022. PHEBUS (Probing of Hermean Exosphere By Ultraviolet Spectroscopy), the UV spectrometer onboard the spacecraft, observed Mercury's exosphere during the flybys at the closest parts of approach to the planet with its two visible channels notably. Mercury is surrounded by a tenuous collisionless atmosphere (exosphere) that contains a variety of species. We report the detection of exospheric calcium with an enhancement near the dawn region. We show that the calcium exosphere is much extended on the morning side, beyond 10,000 km. The observations also reveal a day/night asymmetry of the calcium exosphere. Furthermore, we report the detection of additional species. However, the flyby data alone do not allow us to formally identify the species. Key Points: PHEBUS observed Mercury's extended exosphere of calcium on the morning side beyond ∼10,000 kmThe observed calcium profiles may be explained by the 2D effects of altitude and local timeAdditional species were detected, potentially manganese and potassium [ABSTRACT FROM AUTHOR]

Spectroscopic measurements are a powerful tool to investigate the surface composition of airless bodies and provide clues of their origin. The composition and origin of Phobos and Deimos are still unknown and are currently widely debated. We present spectroscopic measurements of Phobos and Deimos at ultraviolet and visible wavelengths (250–650 nm) made by the NOMAD‐Ultraviolet and Visible Spectrometer (UVIS) on the ExoMars TGO mission. These new spectra cover multiple areas on Phobos and Deimos, and are of generally higher spectral resolution and signal‐to‐noise than previous spectra, and extend to lower wavelengths than most previous measurements. The UVIS spectra confirm a red‐sloped spectrum lacking any strong absorption features; however, we confirm the presence of a previously identified absorption feature near 0.65 μm and tentative absorption near 0.45 μm. The observed Phobos and Deimos spectra are similar to D‐ and T‐type asteroids, adding weight to the captured asteroid hypothesis for the moons' origins. We also find, however, that the UVIS Phobos reflectance spectra of Phobos' red unit is a relatively close match to the olivine‐rich, highly shocked Mars meteorite NWA 2737, with a low overall reflectance, a red‐sloped spectrum, and lack of olivine‐associated absorption bands in the UVIS spectral range. This meteorite, however, exhibits spectral features at longer wavelengths that not observed in the Martian moon spectra, indicating a need for further investigation at longer wavelengths to interpret whether this material could inform our understanding of Phobos' origin. Plain Language Summary: Whether the Martian moons Phobos and Deimos are captured asteroids that originated outside the Mars system or formed from a debris disk around Mars during its formation or following a large impact on Mars is widely debated. Measurements of reflected sunlight from the surfaces of Phobos and Deimos can provide pivotal information on their composition as well as clues to their origins. In this study, we present a comparison between observations of Phobos and Deimos made with the NOMAD Ultraviolet and VIsible Spectrometer (UVIS) on the ExoMars Trace Gas Orbiter (TGO) and previous spectral measurements from other missions. The UVIS spectra show a good agreement with previous observations, with the Phobos and Deimos spectra showing a red‐sloped spectrum similar to primitive carbonaceous chondrite asteroids. A change in the spectral slope at wavelengths longer than 0.53 μm is shown to be consistent with the previously identified 0.65 μm absorption feature. The similarity between the measured Phobos ultraviolet and visible spectrum and highly‐shocked olivine from the Mars meteorite NWA 2737 entices the question of whether Phobos and Deimos surfaces could be composed of a similar dark olivine matrix and formed within the accretion disk created from a giant impact on Mars. Key Points: Phobos and Deimos reflectance spectra have been obtained from the ExoMars NOMAD spectrometer covering 250–650 nmUVIS measurements confirm the spectral similarity of Phobos and Deimos to primitive carbonaceous chondrite asteroidsThe spectrum of Phobos is analogous to some features of shock‐produced dark olivine which could support an alternative planetary origin [ABSTRACT FROM AUTHOR]

We study the variation of temperature and non-thermal velocity with height in fan loops. For this purpose, we have used the observations recorded by the Extreme Ultraviolet Imaging Spectrometer onboard Hinode. We have employed the emission measure (EM)-loci method to estimate the temperatures of different coronal fan loops and then compute the non-thermal velocities using the obtained temperatures in Si  vii 275.35 Å and Fe  viii 185.21 Å lines. The EM-loci analysis provides nearly iso-thermal temperature along the fan loops. We obtain the peak temperatures in the range |$\log \, T(K)$|  = 5.85–5.95 for fan loops, and the subtraction of thermal broadening gives the non-thermal velocities in the range ≈5–15 and 11–29 km s−1 for Si  vii 275.35 Å and Fe  viii 185.21 Å, respectively. Our method provides quantitative accuracy in the measurement of non-thermal velocity, which is an important parameter in understanding the dynamics of heating of the solar atmosphere. [ABSTRACT FROM AUTHOR]

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A novel ultraviolet spectrometer has been developed and tested over 10 years at Lauder, New Zealand. The system, UV2, makes alternating measurements of the global and direct UV irradiance and can therefore be used to measure ozone and aerosol optical depth. After an analysis of the stability of UV2, these measurements, along with UV irradiance are compared to relevant observations made by an additional UV spectrometer (UV4), a Dobson spectrophotometer (#72) and two radiometers measuring aerosol optical depth, a Prede skyradiometer and a Middleton Solar radiometer (SP02). UV2 irradiance is shown to be lower than UV4 by between 2.5-3.5%, with a standard deviation of a similar magnitude. Total column ozone values are shown to agree with Dobson values with a mean bias of 2.57 Dobson units (DU) and standard deviation of 1.15 DU when using the direct sun measurements. Aerosol optical depth at 400-412nm and 500nm agrees to within 0.015 and is comparable to the difference between the reference radiometers. Further work is needed, particularly in the radiometric calibration at longer wavelengths, in order to determine if this instrument can supersede or enhance measurements made by the Dobson or the aerosol radiometers. [ABSTRACT FROM AUTHOR]

Quantifying the global bromine monoxide (BrO) budget is essential to understand ozone chemistry better. In particular, the tropospheric BrO budget has not been well characterized. Here, we retrieve nearly a decade (February 2012–July 2021) of stratospheric and tropospheric BrO vertical columns from the Ozone Mapping and Profiling Suite Nadir Mapper (OMPS-NM) onboard the Suomi National Polar-orbiting Partnership (Suomi-NPP) satellite. To address the mismatch between a priori profiles and column retrievals in the stratosphere-troposphere separation, for each OMPS-NM pixel, we save two types of BrO vertical profiles and use the appropriate one based on whether a tropospheric enhancement is detected. Total ozone columns observed from OMPS-NM are used to identify tropospheric BrO enhancements. We demonstrate good agreement for both the stratosphere (r = 0.81–0.83) and the troposphere (r = 0.50–0.69) by comparing monthly mean BrO vertical columns from OMPS-NM with ground-based observations from three stations (Lauder, Utqiag ̇vik, and Harestua). The OMPS-NM BrO retrievals successfully capture tropospheric enhancements not only in the polar but also in the extrapolar regions (the Rann of Kutch and the Great Salt Lake). We also estimate random uncertainties in the retrievals pixel by pixel, which can assist in quantitative applications of the OMPS-NM BrO dataset. Our BrO retrieval algorithm is designed for cross-sensor applications and can be adapted to other space-borne ultraviolet spectrometers, contributing to the creation of continuous long-term satellite BrO observation records. [ABSTRACT FROM AUTHOR]

We present a novel sensing approach for ambient ozone detection based on deep-ultraviolet (DUV) cavity-enhanced absorption spectroscopy (CEAS) using a laser driven light source (LDLS). The LDLS has broadband spectral output which, with filtering, provides illumination between ~230–280 nm. The lamp light is coupled to an optical cavity formed from a pair of high-reflectivity (R~0.99) mirrors to yield an effective path length of ~58 m. The CEAS signal is detected with a UV spectrometer at the cavity output and spectra are fitted to yield the ozone concentration. We find a good sensor accuracy of <~2% error and sensor precision of ~0.3 ppb (for measurement times of ~5 s). The small-volume (<~0.1 L) optical cavity is amenable to a fast response with a sensor (10–90%) response time of ~0.5 s. Demonstrative sampling of outdoor air is also shown with favorable agreement against a reference analyzer. The DUV-CEAS sensor compares favorably against other ozone detection instruments and may be particularly useful for ground-level sampling including that from mobile platforms. The sensor development work presented here can also inform of the possibilities of DUV-CEAS with LDLSs for the detection of other ambient species including volatile organic compounds. [ABSTRACT FROM AUTHOR]

On 1 October 2021, Bepi‐Colombo performed its first flyby of Mercury. During the maneuver, the short wavelength channel (55–155 nm) of "Probing the Hermean Exosphere by UV Spectroscopy" (PHEBUS) was activated for a total duration of 1 hr. The helium resonance line at 58.4 nm was clearly observed during the whole sequence. At large distance from the planet, the emission was due to helium atoms in the interplanetary medium (interplanetary UV glow). Just after crossing the terminator of the planet and entering the dawn side of the exosphere, PHEBUS observed a clear additional emission due to scattering of solar photons by helium atoms in the exosphere of Mercury. The first detection of the 58.4 nm line in the exosphere of Mercury was reported by Broadfoot et al. (1976, https://doi.org/10.1029/gl003i010p00577) following the Mariner 10 flybys in 1974. The PHEBUS observation of exospheric helium emissions is the first for this element since the UVS measurements. In this paper, we present the results of our analysis of the PHEBUS data at 58.4 nm. Calibration of both instruments are compared with observations of the interplanetary glow, showing that the measurements of both instruments are accurate. However, we find that the exospheric density of helium atoms deduced from the PHEBUS data is 4.5–7.5 times lower than the previous estimate from UVS on Mariner 10. Possible explanations are considered. We show that some of the helium atoms present in the exosphere of Mercury could originate from the local interstellar cloud. Plain Language Summary: On 1 October 2021, The Bepi‐Colombo mission performed its first flyby of Mercury. During this maneuver, the "Probing the Hermean Exosphere by UV Spectroscopy" (PHEBUS) ultraviolet spectrometer was activated for 1 hour, starting 30 min before the time of the closest approach to the surface of Mercury. This instrument is able to measure the emission of helium atoms either in the interplanetary medium or in the tenuous atmosphere of Mercury. The presence of helium atoms around Mercury was first discovered by the ultraviolet spectrograph (UVS) of the Mariner 10 mission in 1974. The observations of PHEBUS confirm the detection of helium atoms in the atmosphere of Mercury. However, the amount of helium atoms detected by PHEBUS is 4.5–7.5 times lower than the value reported by UVS after the Mariner 10 flybys. We discuss possible explanations for this difference. Key Points: This paper presents helium measurements obtained during the first flyby of Mercury by the Bepi‐Colombo missionCalibrations of UVS/Mariner 10 and of PHEBUS are cross‐checked with observations of the interplanetary glow at 58.4 nmThe helium content in the exosphere of Mercury derived by PHEBUS is 4.5–7.5 times lower than the previous estimate from the Mariner 10 mission [ABSTRACT FROM AUTHOR]

Aim. The Isolation of nucleic acid is an important step for conducting different molecular assays in many laboratories around the world. It is also a common practice that user is isolating the ribonucleic acid (RNA) from the samples with mini column once and throwing away the supernatant. This makes isolated RNA as limiting factor in many studies as this issue has not been addressed in literature. Therefore, we decided to conduct whether it is a loss of ribonucleic acid during the mini column isolation method. Method. In this research, we have made analysis whether there is a loss of RNA during the isolation process. The mini column isolations were done with different samples of human tissues from placenta and umbilical cords. These were assessed with spectrometric instrument and real time PCR machine. Results. It was found that there is loss of abundant quantity of RNA during the subsequent isolations. The amount measured with UV spectrometer indicates that some times 2nd and 3rd isolation have more RNA than the first isolation. Realtime PCR for house keeping gene beta actin shows that presence of RNA can be seen up to 6 isolation cycles from supernatants. Conclusion. There is loss of RNA in subsequent isolations with mini column method, therefore it is possible to isolate more RNA from the next supernatant isolations. User should do the multiple isolations to get higher yield of RNA. [ABSTRACT FROM AUTHOR]

The Trace Gas Orbiter has been orbiting Mars since 2016 with the Nadir and Occultation for MArs Discovery (NOMAD) UltraViolet and Visible Spectrometer (UVIS) instrument on board. Focusing on limb observations recorded in the ultraviolet (UV) part of the NOMAD/UVIS spectra, we describe here the CO Cameron bands, CO2+ ${\mathrm{C}\mathrm{O}}_{2}^{+}$ UV doublet and Fox‐Duffendach‐Barker (FDB) bands and [OI] UV emissions. Averaged limb profiles are presented, showing that the strongest brightness and the highest peak altitudes are reached near perihelion. Ratios between the UV emissions are also estimated and compared with previous observations from Mariner and Mars Express. NOMAD/UVIS is the first instrument able to simultaneously acquire data both in the UV and the visible in the Mars atmosphere so that the oxygen green line at 557.7 nm and its UV counterpart at 297.2 nm, both originating from the same O(1S) upper state level, may be directly compared. A mean ratio of 15.8 is derived, in close agreement with ab initio calculations. The spectral composition of the CO2+ ${\mathrm{C}\mathrm{O}}_{2}^{+}$ FDB system that has not been observed entirely since the Mariner missions in the 1970s is analyzed. According to the spectral composition of the FDB bands, we show that this emission is produced at ∼70% by photoionization of CO2 (which populates the shorter wavelengths of the spectrum) and ∼30% by resonance scattering of solar radiation (which populates longer wavelengths). No evidence of a change with altitude in the CO2+ ${\mathrm{C}\mathrm{O}}_{2}^{+}$ FDB spectral composition is observed in the NOMAD/UVIS spectra. Plain Language Summary: Dayglow is an atmospheric emission occurring on the illuminated side of a planet. This phenomenon occurs when atmospheric atoms or molecules interact with incoming solar radiation that produce excited atoms and molecules. When these atoms and molecules de‐excite radiatively, they release photons at specific wavelengths and altitudes, generating airglow. Several space missions since the 1970s observed the Mars ultraviolet (UV) dayglow. The Nadir and Occultation for MArs Discovery (NOMAD)/UltraViolet and Visible Spectrometer (UVIS) instrument, currently orbiting Mars since 2016, is providing new insights on this phenomenon. In this study, we describe the results of the observations of the Martian UV dayglow by NOMAD/UVIS. We show that the strongest emissions occur at higher altitudes, when the planet is closest to the Sun. We also estimate the intensity ratios between the emissions and compare our results with previous observations from Mariner and Mars Express. The CO2+ ${\mathrm{C}\mathrm{O}}_{2}^{+}$ emission between 300 and 400 nm is also detected for the first time since the Mariner missions in the 1970s. The production mechanisms can be deduced by analyzing the spectral distribution of this emission. We conclude that photoionization of CO2 represents ∼70% of its production, while resonance scattering of solar radiation accounts for ∼30%. This proportion was predicted by models, but this is the first time that observations validate these simulations. This statement is true at all the observed altitudes. Key Points: The Mars ultraviolet (UV) dayglow emissions from CO Cameron, CO2+ ${\mathrm{C}\mathrm{O}}_{2}^{+}$ ultraviolet doublet, [OI] UV and CO2+ ${\mathrm{C}\mathrm{O}}_{2}^{+}$ Fox‐Duffendach‐Barker (FDB) are analyzed using Nadir and Occultation for MArs Discovery/UltraViolet and Visible Spectrometer limb spectraThe controversial 557.7/297.2 nm intensity ratio derived from those simultaneous measurements is highly reliably determinedThe full wavelength range of the CO2+ ${\mathrm{C}\mathrm{O}}_{2}^{+}$ FDB band system is detected for the first time since Mariner [ABSTRACT FROM AUTHOR]

The Mars Atmosphere and Volatile Evolution (MAVEN) mission instrument suite includes an ultraviolet echelle spectrograph with high‐spectral resolution designed to resolve D and H Lyman‐α emissions. The high‐spectral resolution mode was previously characterized in the lab and in the cruise phase to Mars and had been calibrated using observations and models of interplanetary hydrogen Lyman‐α emissions. This work presents improved characterizations of the high‐spectral resolution mode using in‐orbit observations that allow for more robust detections of the faint D Lyman‐α emission line. Additionally, the instrument was re‐calibrated using simultaneous and comparable observations made with the Hubble Space Telescope high‐spectral resolution instrument. Comparisons to Lyman‐α observations made with the low‐resolution UV channel on the spectrometer, that had been calibrated with stars, showed consistency in the brightness values for measurements obtained at similar observational conditions. The combined upgrades to the faint‐emission fitting and new calibration techniques of the MAVEN echelle channel have resulted in an improved data‐reduction pipeline with favorable implications for the science utility of D and H Lyman‐α emissions. Plain Language Summary: The MAVEN high resolution echelle (ECH) instrument has been used to observe ultraviolet emissions from Mars. Measurements made with MAVEN/ECH were made available to the public by using a data reduction pipeline that had been developed with in‐lab and theoretical analysis to convert observations into a form that was useable by the broader scientific community. Since MAVEN's orbit insertion in 2014, the ECH detector has been better characterized with lessons learned from in‐orbit performance. These improvements produced a new data reduction pipeline that has enhanced the detection of faint D Lyman‐α emissions that are critical to interpreting water loss from the upper atmosphere of Mars. Key Points: MAVEN/ECH uses HST/STIS, the only other UV echelle instrument deployed to space, for calibration and independent verificationThe MAVEN/ECH data reduction algorithm has been upgraded to improve detection of faint D Lyman‐α emissionsThe scientific implications of this work include doubling the previous data set of D measurements available for reliable interpretation [ABSTRACT FROM AUTHOR]

The M1.5-class flare and associated coronal mass ejection (CME) of 16 February 2011 was observed with the Extreme ultraviolet Imaging Spectrometer on board the Hinode spacecraft. Spray plasma associated with the CME is found to exhibit a Doppler blue-shift of 850 km s−1 – one of the largest values reported from spectroscopy of the solar disk and inner corona. The observation is unusual in that the emission line (Fe xii 193.51 Å) is not observed directly, but the Doppler shift is so large that the blue-shifted component appears in a wavelength window at 192.82 Å, intended to observe lines of O v , Fe xi and Ca xvii. The Fe xii 195.12 Å emission line is used as a proxy for the rest component of 193.51 Å. The observation highlights the risks of using narrow wavelength windows for spectrometer observations when observing highly-dynamic solar phenomena. The consequences of large Doppler shifts for ultraviolet solar spectrometers, including the upcoming Multi-slit Solar Explorer (MUSE) mission, are discussed. [ABSTRACT FROM AUTHOR]

Two pairs of space-resolved extreme ultraviolet (EUV) spectrometers working at 5–138 Å with different vertical observation ranges of −7 ≤ Z ≤ 19 and −18 ≤ Z ≤ 8 cm have been newly developed to observe the radial profile of impurity line emissions and to study the transport of high-Z impurity ions intrinsically existing in EAST tokamak plasmas. Both spectrometers are equipped with a complementary metal-oxide semiconductor (CMOS) detector (Andor Marana-X 4.2B-6, Oxford Instruments) with sensitive area of 13.3 × 13.3 mm2 and number of pixels equal to 2048 × 2048 (6.5 × 6.5 µm2/pixels). Compared to the currently operating space-resolved EUV spectrometers with a charge-coupled detector (CCD: 1024 × 255 pixels, 26 × 26 µm2) working at 30–520 Å, this spectrometer's performance was substantially improved by using the CMOS detector. First, the spectral resolution measured at full width at half maximum was improved in the whole wavelength range, e.g., Δλ1/2_CMOS = 0.092 Å and Δλ1/2_CCD = 0.124 Å at C VI 33.73 Å and Δλ1/2_CMOS = 0.104 Å and Δλ1/2_CCD = 0.228 Å at Mo XXXI 115.999 Å, thus enabling a more accurate analysis of spectra with complicated structure such as tungsten unresolved transition array in the range 45–65 Å. Second, the temporal resolution was largely improved due to the high-speed data acquisition system of the CMOS detector, e.g., Δt_CMOS = 15 ms/frame and Δt_CCD = 200 ms/frame at routine operation in the radial profile measurement. Third, signal saturation issues that occurred when using the old CCD sensor during impurity accumulation now disappeared entirely using the CMOS detector due to lower exposure time at high readout rates, which largely improved the observation performance in similar impurity burst events. The above-mentioned performance improvements of the space-resolved EUV spectrometer led to a rapid change in the W XXXIII (52.22 Å) radial profile during a single cycle of low-frequency sawtooth oscillation with fst = 5–6 Hz at a sufficient detector count rate. [ABSTRACT FROM AUTHOR]

Mars' ultraviolet dayglow has been used to study its upper atmosphere for over four decades. Identifying variations in emission features has provided information on composition, density, and temperature. The Emirates Mars Ultraviolet Spectrometer onboard the Emirates Mars Mission observes Mars' dayglow at Far and Extreme UV wavelengths. Variations in disk emission features are studied, with a focus on O I 130.4, CO Fourth Positive Group and C I 156.1 nm. All show variations with local time (LT) and emission angle as expected. Dawn‐dusk asymmetry observed is attributed to LT differences in advection. Variations in the brightness of several dayglow features, including 130.4 nm, with irregular shapes are noted in around 25% of the disk images. These display some LT and hemispheric asymmetry in their occurrence rates. Examination of their spatial structure, occurrence, and spectra suggests these are associated with variations in composition and photoelectron flux. Plain Language Summary: Measurements of ultraviolet light coming from Mars' upper atmosphere has been used to measure its properties. From the color and brightness of the light, it is possible to identify both what chemical species are present in this region, their temperature and other information. The Emirates Mars Ultraviolet Spectrometer onboard the Emirates Mars Mission makes observations of this ultraviolet light in wavelength regions described as far and extreme ultraviolet. This study looks at emissions of far ultraviolet light that correspond to oxygen atoms, carbon monoxide, and carbon dioxide molecules. The circulation of gases in the upper atmosphere results in a difference in the brightness of these emissions between dawn and dusk. This study also introduces observations of irregularly shaped bright patches in these emissions. The shape, location, and spectra of these suggest they are the result of changes in the chemical composition of the upper atmosphere. Key Points: Variations in the ultraviolet dayglow from the Martian thermosphere with local time (LT) and emission viewing angle are characterizedAsymmetry in the dayglow between dawn and dusk varies by emission from +15.4% to −12.3% in response to transport and temperaturePatches of significant dayglow brightness increase are observed that appear to result from changes in composition and photoelectron flux [ABSTRACT FROM AUTHOR]

A novel Barium Titanate-Zinc ferrite (BaxTiO3-ZnXFe2O4) heterostructure nanocomposites are synthesized at temperatures less than 500ºC which is the major theme of the present research. The synthesis technique is adapted in such a way that the size of the particle is governable. In this research two dissimilar ratios of BTO (hard-site) and ZFO (soft-site) composites are synthesized (H-S 90:10, H-S 60:40) and quantitatively analyzed for their exclusive structural, textural, spectroscopic, and optical properties. With XRD data, structural refinement has been carried out showing 49 % of harder-BTO phase (Triclinic) and 51% of softer-ZFO phase (Cubic) for H-S 90:10 and similarly 78% of harder-BTO phase and 22% of softer-ZFO phase in the H-S 60:40 composite respectively. Very small particles of 6nm are found which is confirmed by SEM histogram and sample purity was determined using EDX analysis. Proofs for the formation of nanocomposites and the existence of Tetrahedral and Octahedral phases for each sample were given using FTIR Spectroscopy. From UV spectrometer data, Tauc’s plot is used to find the wide energy band gap which is observed to be 2.6651 and 3.1971 eV, thus proving that these composites can present themselves as a budding candidate for nano-level optoelectronic devices and other photovoltaic applications. [ABSTRACT FROM AUTHOR]

We have obtained constraints on the nanoflare energy distribution and timing for the heating of a coronal bright point. Observations of the bright point were made using the Extreme Ultraviolet Imaging Spectrometer on Hinode in slot mode, which collects a time series of monochromatic images of the region leading to unambiguous temperature diagnostics. The Enthalpy-Based Thermal Evolution of Loops model was used to simulate nanoflare heating of the bright point and generate a time series of synthetic intensities. The nanoflare heating in the model was parameterized in terms of the power-law index α of the nanoflare energy distribution, which is ∝ E âˆ' α ; average nanoflare frequency f ; and the number N of magnetic strands making up the observed loop. By comparing the synthetic and observed light curves, we inferred the region of the model parameter space (α, f, N) that was consistent with the observations. Broadly, we found that N and f are inversely correlated with one another, while α is directly correlated with either N or f. These correlations are likely a consequence of the region requiring a certain fixed energy input, which can be achieved in various ways by trading off among the different parameters. We also find that a value of α > 2 generally gives the best match between the model and observations, which indicates that the heating is dominated by low-energy events. Our method of using monochromatic images, focusing on a relatively simple structure, and constraining nanoflare parameters on the basis of statistical properties of the intensity provides a versatile approach to better understand the nature of nanoflares and coronal heating. [ABSTRACT FROM AUTHOR]

The Emirates Mars Ultraviolet Spectrometer (EMUS) is a far ultraviolet spectrometer on‐board the Emirates Mars Mission's (EMM) which arrived at Mars on 9 February 2021. EMUS is designed to observe key neutral species in the Martian thermosphere (100–200 km) and exosphere (≥200 km). EMUS has observed two neutral argon (Ar) emission lines, Ar I 104.8 nm and Ar I 106.6 nm, in the thermosphere. Our interest in these emissions stem from argon's non‐reactiveness, making it a tracer for transport between the upper and lower atmosphere. We report average argon disk brightness measured by EMUS and compare them to measurements from Earth orbiting observatories. For the first time, this work investigates the variability of Ar I 106.6 nm brightness due to emission angles, solar zenith angles, solar longitudes, local times and latitudes. To contrast the behavior of inert argon we compare these results with the photochemically reactive oxygen 135.6 nm. Plain Language Summary: The Emirates Mars Ultraviolet Spectrometer (EMUS), on board of the Emirates Mars Mission, measures airglow from the upper atmosphere of Mars. Here we report on the first disk images of argon gas at Mars and compare them to past observations. We also compare the brightness of the argon to a well‐studied oxygen airglow feature. The optical depth of the argon airglow and how it is excited are discussed. Key Points: Emirates Mars Ultraviolet Spectrometer's (EMUS) provides first disk resolved images of argon in the thermosphere of MarsEMUS average disk brightness of argon I 104.8 nm and argon I 106.6 nm align with previous measurements reported in literatureArgon I 106.6 nm is found to be optically thick and stimulated by fluorescent scattering as well as electron impact [ABSTRACT FROM AUTHOR]

The aim of this study is to fabricate novel chitosan-based film loaded with curcumin loaded metal-phenolic nanoparticles (MPN@Cur NPs) as an active agent for food preservation. The average particle size and ζ-potential of the MPN@Cur NPs were determined to be 205.9 nm and −26.8 mV, respectively. The impact of incorporating MPN@Cur NPs upon the morphology, microstructure, physicochemical characteristics, and functional activities of CS-based films were investigated through scanning electron microscope, infrared spectrometer, X-ray diffractometer, ultraviolet spectrometer, antioxidant activity and antibacterial activity analysis. The outcomes indicated that MPN@Cur NPs exhibited good mechanical compatibility with chitosan, effectively filling voids within the film matrix and significantly enhancing its mechanical characteristics (e.g., elongation at break improved from 22.6% to 37.3%; tensile strength improved from 31.1 MPa to 43.6 MPa). Additionally, films incorporating MPN@Cur NPs displayed superior barrier properties (e.g., water vapor and oxygen transmission), enhanced thermal stability, and improved UV-blocking capabilities compared to pure CS films (transmittance for UV decreased from 93.6% to 35.3%). Moreover, these films exhibited a marked increase in antibacterial efficacy against the foodborne pathogens Staphylococcus aureus and Escherichia coli , as well as elevated antioxidant activity (e.g., scavenging capability for DPPH increased from 9.22% to 85.19%, ABTS increased from 8.62% to 80.02%). Ultimately, the CS-based film significantly prolonged the shelf life of milk stored at 25 °C. Therefore, nanocomposite films provide an attractive and promising pathway for the high value-added commercial use of chitosan in food conservation. [Display omitted] • The films were fabricated by incorporating MPN@Cur NPs into CS matrix. • The films presented excellent antioxidant and antibacterial activities. • The film could effectively prolong the shelf life of milk. [ABSTRACT FROM AUTHOR]

[Display omitted] • The carbon dots-metal complex was synthesized by adding metal ions to the carbon point solution. • Using Carbon Dots@Metal complex as fluorescent probes for substance detection. • Detection of MnO 4 - by fluorescence enhancement. • Remarkably low detection limit, linearity, and selectivity for MnO 4 - inspection. Nitrogen-doped carbon quantum dots (NCQDs) with bright yellow fluorescence (quantum yield of 27.3 %) were synthesized via a solvothermal method using 2,3-diaminopyridine as the carbon and nitrogen source and ethanol as the solvent. Subsequently, the NCQDs were reacted with Cu2+ in an aqueous solution, forming nitrogen-doped carbon quantum dots-copper complexes (NCQDs@Cu) with great potential for selective determination of MnO 4 - ions. The aqueous solution of NCQDs@Cu exhibiting a very weak fluorescence (quantum yield of 2.2 %) demonstrated a significant enhancement (quantum yield of 10.0 %) upon interaction with MnO 4 -(Turn-on). Furthermore, this enhancement remained unaffected by the interfering conventional or unconventional explosives, inorganic ions, and oxidants. Moreover, a good linear relationship existed between the fluorescence intensity of the NCQDs@Cu and the concentration of the permanganate ions in a range of 0 to 5 μmol/L with a detection limit of 32.4 nmol/L. Additionally, the study investigated the underlying principles of the detection mechanism using advanced technologies such as X-ray photoelectron spectroscopy(XPS), The Fourier-transform infrared (FTIR), ultraviolet visible spectrometer (UV–Vis), fluorescence spectrometer and other methods. Finally, the NCQDs@Cu were successfully applied for detecting MnO 4 - in simulated and actual unconventional explosives, demonstrating a good correlation with standard methods. Therefore, the developed NCQDs@Cu can be used for rapid on-site inspection in explosive incident scenarios. This new method of using carbon dots-metal complexes as fluorescent probes will also provide new ideas for researchers. [ABSTRACT FROM AUTHOR]

[Display omitted] • A critical review of the advancements in optical bio (sensors) for the detection of essential amino acids. • Sensing mechanisms fundamental to colorimetric detection are discussed. • Synergy between nanotechnology and sensing through signal transduction and amplification has been presented. • The potential and challenges of optical sensors are reviewed.. The rapid advancements in optical sensor research over the past decade have yielded significant progress, owing to their numerous advantages over conventional methods. These advantages primarily stem from their operational simplicity and cost-effectiveness. Particularly, optical sensors offer a colorimetric response that can be easily determined by the naked eye or ultraviolet spectrometer, exhibiting exceptional selectivity. Nanoparticles have found diverse applications across various fields, greatly enhancing numerous aspects of our lives. A predominantly promising opportunity lies in their prospective applications for the detection of essential amino acids, due to their distinctive optical properties. Essential amino acids have an important part in numerous bodily functions and serve as diagnostic indicators for several diseases, given their imbalanced levels within the human body. Therefore, it is crucial to develop a simple approach for the identification and quantification of essential amino acids. However, several challenges still inhibit the full potential of these systems for on-site essential amino acid monitoring. These challenges include ensuring color homogeneity, analyzing real samples, and managing data effectively. Consequently, this comprehensive review explores the progress and challenges associated with the application of nanoparticle-based colorimetric techniques for the detection of essential amino acids under optimized conditions. Furthermore, we explore the fundamental mechanisms for the development of these analytical techniques. Finally, we aim to discuss future directions and opportunities in colorimetric techniques, highlighting their potential as a crucial component of advanced analytical approaches. [ABSTRACT FROM AUTHOR]

The Extreme ultraviolet Imaging Spectrometer (EIS) on board the Hinode spacecraft has been operating since 2006, returning high-resolution data in the 170 – 212 and 246 – 292 Å wavelength regions. EIS has four slit options, with the narrow 1′′ and 2′′ slits used for spectroscopy and the wide 40′′ and 266′′ slits used for monochromatic imaging. In this article several properties of the 40′′ slit (or slot) are measured using the Fe xii 195.12 Å line, which is formed at 1.5 MK. The projected width of the slot on the detector shows a small variation along the slit with an average value of 40.949′′. The slot image is tilted on the detector and a quadratic formula is provided to describe the tilt. The tilt corresponds to four pixels on the detector and the slot centroid is offset mostly to the right (longer wavelengths) of the 1′′ slit by up to four pixels. Measurement of the intensity decrease at the edge of the slot leads to an estimate of the spatial resolution of the images in the x -direction. The resolution varies quadratically along the slot, with a minimum value of 2.9′′ close to the detector center. Intensities measured from the slot images are found to be on average 14% higher than those measured from the 1′′ slit at the same spatial location. Background subtraction is necessary to derive accurate intensities in quiet-Sun and coronal-hole regions. Prescriptions for deriving accurate slot intensities for different types of slot datasets are presented. [ABSTRACT FROM AUTHOR]

These are the memoirs of fifty years of research in solar physics, closely related to the history of three of the major solar space missions, from the Solar Maximum Mission, SMM, to Solar Orbiter, at present in navigation toward vantage points closer and closer to the Sun. My interest in solar physics was stimulated by the studies on cosmic rays at the University of Turin, and the research in this field initiated at Stanford University as a postdoctoral fellow in the team of John Wilcox with studies on the large-scale corona and its rotation. Thanks to Alan Gabriel, during my first space mission, SMM, I was involved in the operations and scientific data analysis of the Soft X-ray Polychromator. Together with Giancarlo Noci and Giuseppe Tondello, I participated in the realization of the UltraViolet Coronagraph Spectrometer, NASA/ASI, flown on-board SOHO. After this experience there was the opportunity to participate in the formulation of the proposal of the Solar Orbiter mission, and to guide the team, which for this mission developed the Metis coronagraph, up to the delivery of the instrument to the European Space Agency in 2017. [ABSTRACT FROM AUTHOR]

The Nadir Mapper (NM) and Nadir Profiler (NP) within the Ozone Mapping and Profiler Suites (OMPS) are ultraviolet spectrometers to measure Earth radiance and Solar irradiance spectra from 300–380 nm and 250–310 nm, respectively. The OMPS NM and NP instruments flying on the Suomi-NPP (SNPP) satellite have provided over ten years of operational Sensor Data Records (SDRs) data sets to support a variety of OMPS Environmental Data Record (EDR) applications. However, the discrepancies of quality remain in the operational OMPS SDR data prior to 28 June 2021 due to changes in calibration algorithms associated with the calibration coefficient look-up tables (LUTs) during this period. In this study, we present results for the newly ( v 2 ) reprocessed SNPP OMPS NM and NP SDR data prior to 30 June 2021, which uses consistent calibration tables with improved accuracy. Compared with a previous ( v 1 ) reprocessing, this new reprocessing includes the improvements associated with the following updated tables or error correction: an updated stray light correction table for the NM, an off-nadir geolocation error correction for the NM, an artificial offset error correction in the NM dark processing code, and biweekly solar wavelength LUTs for the NP. This study further analyzes the impact of each improvement on the quality of the OMPS SDR data by taking advantage of the existing OMPS SDR calibration/validation studies. Finally, this study compares the v 2 reprocessed OMPS data sets with the operational and the v 1 reprocessed data sets. The results demonstrate that the new reprocessing significantly improves the accuracy and consistency of the life-time SNPP OMPS NM and NP SDR data sets. It also advances the uniformity of the data over the dichroic range from 300 to 310 nm between the NM and NP. The normalized radiance differences at the same wavelength between the NM and NP observations are reduced from 0.001 order ( v 1 reprocessing) or 0.01 order (operational processing) to 0.001 order or smaller. The v 2 reprocessed data are archived in the NOAA CLASS data center with the same format as the operational data. [ABSTRACT FROM AUTHOR]

The Ultraviolet and Visible Spectrometer Ultraviolet (UVIS UV) and Visible Spectrometer channel of the Nadir and Occultation for MArs Discovery spectrometer aboard the ExoMars Trace Gas Orbiter has made limb observations of the Martian dayglow during more than a Martian year. Two pointing modes have been applied: (a) In the inertial mode, the spectrometer scans the atmosphere twice down to near the surface and provides altitude profiles of the dayglow; (b) in the tracking mode, the atmosphere is scanned at varying latitudes at a nearly constant altitude through the entire observation. We present a statistical study of the vertical and seasonal distribution of the recently discovered oxygen green and red lines at 557.7 nm and 630 nm. It indicates that the brightness of the green line emission responds to changes in the Lyman‐α flux. The peak altitude of the green line emission increases seasonally when the Sun‐Mars distance decreases. The lower peak of the green line statistically drops by 15–20 km between perihelion and aphelion at mid‐to high altitude. The main lower peak intensity shows an asymmetry between the two hemispheres. It is significantly brighter and more pronounced in the southern hemisphere than in the north. This is a consequence of the stronger Lyman‐α solar flux near perihelion. The second component of the oxygen red line at 636.4 nm is also detected for the first time in the Martian atmosphere. A photochemical model is used to simulate the variations of the green dayglow observed along limb tracking orbits. Plain Language Summary: The Ultraviolet and Visible Spectrometer (UVIS) instrument aboard the ExoMars Trace Gas Orbiter made it possible to observe the visible emissions that occur on the dayside of the Mars atmosphere during more than a Martian year. Among them, the emissions of the oxygen called "green line" and "red line" (because of their wavelength of 557.7 nm and 630 nm, respectively), which are analyzed over time and can be used as proxies to study the changes in the upper atmosphere of Mars. We show that these emissions occur at higher altitudes and are brighter when Mars is closer to the Sun. We also show evidence of the presence of the second component of the red line at 636.4 nm, which confirms the identification of the recently discovered 630 nm emission. While the green line is composed of two peaks near 80 and 120 km, the red line limb brightness presents a broad peak near 140 km. Finally, we show that a photochemical model simulates the UVIS data very well. Key Points: Nadir and Occultation for MArs Discovery/Ultraviolet and Visible Spectrometer limb observations of the green line dayglow show large seasonal variability in both the peak altitude and brightnessWe bring evidence of the presence of the second component of the oxygen red line at 636.4 nmModel simulations confirm that the Sun‐Mars distance controls the altitude and the brightness of both oxygen emissions [ABSTRACT FROM AUTHOR]

We present joint Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) and Interface Region Imaging Spectrograph (IRIS) observations of Fe xii lines in active regions, both on-disk and off-limb. We use an improved calibration for the EIS data, and find that the 192.4 Ă.../1349 Ă... observed ratio is consistent with the values predicted by CHIANTI and the coronal approximation in quiescent areas, but not in all active-region observations, where the ratio is often lower than expected by up to a factor of about two. We investigate a number of physical mechanisms that could affect this ratio, such as opacity and absorption from cooler material. We find significant opacity in the EIS Fe xii 193 and 195 Ă... lines, but not in the 192.4 Ă... line, in agreement with previous findings. As we cannot rule out possible EUV absorption by H, He, and He ii in the on-disk observations, we focus on an off-limb observation where such absorption is minimal. After considering these, as well as possible nonequilibrium effects, we suggest that the most likely explanation for the observed low Fe xii 192.4 Ă.../1349 Ă... ratio is the presence of non-Maxwellian electron distributions in the active regions. This is in agreement with previous findings based on EIS and IRIS observations independently. [ABSTRACT FROM AUTHOR]

We describe the energy budget of a coronal mass ejection (CME) observed on 1999 May 17 with the Ultraviolet Coronagraph Spectrometer (UVCS). We constrain the physical properties of the CME’s core material as a function of height along the corona by using the spectra taken by the single-slit coronagraph spectrometer at heliocentric distances of 2.6 and 3.1 solar radii. We use plasma diagnostics from intensity ratios, such as the O vi doublet lines, to determine the velocity, density, temperature, and nonequilibrium ionization states. We find that the CME core’s velocity is approximately 250 km sâˆ'1, and its cumulative heating energy is comparable to its kinetic energy for all of the plasma heating parameterizations that we investigated. Therefore, the CME’s unknown heating mechanisms have the energy to significantly affect the CME’s eruption and evolution. To understand which parameters might influence the unknown heating mechanism, we constrain our model heating rates with the observed data and compare them to the rate of heating generated within a similar CME that was constructed by the MAS code’s 3D MHD simulation. The rate of heating from the simulated CME agrees with our observationally constrained heating rates when we assume a quadratic power law to describe a self-similar CME expansion. Furthermore, the heating rates agree when we apply a heating parameterization that accounts for the CME flux rope’s magnetic energy being converted directly into thermal energy. This UVCS analysis serves as a case study for the importance of multislit coronagraph spectrometers for CME studies. [ABSTRACT FROM AUTHOR]

The Emirates Mars Mission (EMM) Hope probe was launched on 20 July 2020 at 01:58 GST (Gulf Standard Time) and entered orbit around Mars on 9 Feb 2021 at 19:42 GST. The high-altitude orbit (19,970 km periapse, 42,650 km apoapse altitude, 25° inclination) with a 54.5 hour period enables a unique, synoptic, and nearly-continuous monitor of the Mars global climate. The Emirates Mars Ultraviolet Spectrometer (EMUS), one of three remote sensing instruments carried by Hope, is an imaging ultraviolet spectrograph, designed to investigate how conditions throughout the Mars atmosphere affect rates of atmospheric escape, and how key constituents in the exosphere behave temporally and spatially. EMUS will target two broad regions of the Mars upper atmosphere: 1) the thermosphere (100–200 km altitude), observing UV dayglow emissions from hydrogen (102.6, 121.6 nm), oxygen (130.4, 135.6 nm), and carbon monoxide (140–170 nm) and 2) the exosphere (above 200 km altitude), observing bound and escaping hydrogen (121.6 nm) and oxygen (130.4 nm). EMUS achieves high sensitivity across a wavelength range of 100–170 nm in a single optical channel by employing "area-division" or "split" coatings of silicon carbide (SiC) and aluminum magnesium fluoride (Al+MgF2) on each of its two optical elements. The EMUS detector consists of an open-face (windowless) microchannel plate (MCP) stack with a cesium iodide (CsI) photocathode and a photon-counting, cross-delay line (XDL) anode that enables spectral-spatial imaging. A single spherical telescope mirror with a 150 mm focal length provides a 10.75° field of view along two science entrance slits, selectable with a rotational mechanism. The high and low resolution (HR, LR) slits have angular widths of 0.18° and 0.25° and spectral widths of 1.3 nm and 1.8 nm, respectively. The spectrograph uses a Rowland circle design, with a toroidally-figured diffraction grating with a laminar groove profile and a ruling density of 936 gr mm−1 providing a reciprocal linear dispersion of 2.65 nm mm−1. The total instrument mass is 22.3 kg, and the orbit-average power is less than 15 W. [ABSTRACT FROM AUTHOR]

In this paper, we propose a compact extreme ultraviolet high-throughput spectrometer covering the 50–70 eV energy band. The key element in this spectrometer is a multilayer varied-line-spacing grating that operates in near-normal incidence geometry. The spectrometer can obtain one order of magnitude higher throughput compared to the traditional grazing incidence grating spectrometer in this energy band. The spectrum collection time and sample radiation damage can be largely reduced using the presented design. [ABSTRACT FROM AUTHOR]

Chromatographic analysis shows that the ionic nanostructured complex of the FS-1 drug contains nanocomplexes of κ-dextrin with a size of ~40-48 Å. Based on good agreement between the UV spectra of the model structures and the experimental spectrum of the FS-1 drug, the structure of the active FS-1 nanocomplex is proposed. The structure of the active centers of the drug in the dextrin ring was calculated using the quantum-chemical approach DFT/B3PW91. The active centers, i.e., a complex of molecular iodine with lithium halide (I), a binuclear complex of magnesium and lithium containing molecular iodine, triiodide (II), and triiodide (III), are located inside the dextrin helix. The polypeptide outside the dextrin helix forms a hydrogen bond with dextrin in Complex I and coordinates the molecular iodine in Complex II. It is revealed that the active centers of the FS-1drug can be segregated from the dextrin helix and form complexes with DNA nucleotide triplets. The active centers of the FS-1 drug are only segregated on specific sections of DNA. The formation of a complex between the DNA nucleotide and the active center of FS-1 is a key stage in the mechanisms of anti-HIV, anti-coronavirus (Complex I) and antibacterial action (Complex II). [ABSTRACT FROM AUTHOR]

We present the kinetic Monte-Carlo model, which was developed to describe the influence of a proton flux from the undisturbed solar wind on the daytime atmosphere of Mars. For the first time, the degradation of the solar-wind proton spectrum in the cascade charge-exchange process in the extended hydrogen corona of Mars has been self-consistently modeled; and the energy fluxes and energy spectra of hydrogen atoms penetrating into the daytime upper atmosphere through the boundary of the induced magnetosphere have been determined. The obtained characteristics make it possible to model numerically the proton auroral phenomena observed in the upper atmosphere of Mars with the Imaging Ultraviolet Spectrometer onboard the Mars Atmosphere and Volatile Evolution spacecraft. In our future studies, we plan to compare the results of these calculations to those of observations, which will provide a unique opportunity to determine more accurately the properties of the atmosphere and the magnetic field of Mars, as well as will improve the techniques for determining the solar wind parameters. [ABSTRACT FROM AUTHOR]

Extreme ultraviolet (EUV) source produced by laser-induced discharge plasma (LDP) is a potential technical means in inspection and metrology. A pulsed Nd:YAG laser is focused on a tin plate to produce an initial plasma thereby triggering a discharge between high-voltage electrodes in a vacuum system. The process of micro-pinch formation during the current rising is recorded by a time-resolved intensified charge couple device camera. The evolution of electron temperature and density of LDP are obtained by optical emission spectrometry. An extreme ultraviolet spectrometer is built up to investigate the EUV spectrum of Sn LDP at 13.5 nm. The laser and discharge parameters such as laser energy, voltage, gap distance, and anode shape can influence the EUV emission. [ABSTRACT FROM AUTHOR]

The Ultraviolet Spectrograph (UVS) instrument on the Juno mission records far‐ultraviolet reflected sunlight from Jupiter. These spectra are sensitive to the abundances of chemical species in the upper atmosphere and to the distribution of the stratospheric haze layer. We combine observations from the first 30 perijoves of the mission in order to study the meridional distribution of acetylene (C2H2) in Jupiter's stratosphere. We find that the abundance of C2H2 decreases toward the poles by a factor of 2–4, in agreement with previous analyses of mid‐infrared spectra. This result is expected from insolation rates: near the equator, the UV solar flux is higher, allowing more C2H2 to be generated from the UV photolysis of CH4. The decrease in abundance toward the poles suggests that horizontal mixing rates are not rapid enough to homogenize the latitudinal distribution. Plain Language Summary: The Ultraviolet Spectrograph instrument on the Juno mission to Jupiter is primarily used to study the planet's ultraviolet auroras, but also records reflected sunlight from the planet's upper atmosphere. These ultraviolet reflected sunlight observations can be used to measure the abundances of different gases in Jupiter's stratosphere. In this study, we focus on one prominent molecule, acetylene, and study how its abundance varies with latitude. We find that its abundance decreases toward Jupiter's poles, which agrees with previous results obtained from studying the same molecule with infrared observations. Key Points: Ultraviolet reflected sunlight observations from Juno Ultraviolet Spectrograph were used to study the C2H2 abundance in Jupiter's stratosphereThe stratospheric C2H2 abundance decreases at high latitudes, in agreement with previous studies using infrared dataThe latitudinal distribution of C2H2 can be used to constrain horizontal mixing rates [ABSTRACT FROM AUTHOR]

Ultraviolet spectral imaging has been a powerful tool to investigate the cloud top of Venus, allowing for measurement of several minor gases (especially SO 2 , SO, O 3), of cloud top aerosol's microphysical properties and of atmospheric dynamics through tracking of the unevenly distributed UV absorber. After a brief review of recent UV instruments that orbited around Venus, we present the results of a state-of-the-art radiative transfer model from Marcq et al. (2020) to derive the spectral resolution and Signal-to-Noise ratio (SNR) required to derive abundances of these gases, retrieve optical properties of the aerosols beyond our current knowledge. This leads us to propose a two-channel UV hyperspectral push-broom imager called VeSUV (standing for Venusian Spectroscopy in UV) whose technical characteristics will improve on existing measurements by a factor of at least 2, and which is well suited to the integration into the payload of future low Venus orbit platforms such as the proposed EnVision mission to ESA M5 call. [ABSTRACT FROM AUTHOR]

Satellite estimates of surface UV irradiance have been available since 1978 from the TOMS UV spectrometer and have continued with significantly improved ground resolution using the Ozone Monitoring Instrument (OMI 2004–current) and Sentinel 5 Precursor (S5P 2017–current). The surface UV retrieval algorithm remains essentially the same: it first estimates the clear-sky UV irradiance based on measured ozone and then accounts for the attenuation by clouds and aerosols, applying two consecutive correction factors. When estimating the total aerosol effect in surface UV irradiance, there are two major classes of aerosols to be considered: (1) aerosols that only scatter UV radiation and (2) aerosols that both scatter and absorb UV radiation. The former effect is implicitly included in the measured effective Lambertian-equivalent scene reflectivity (LER), so the scattering aerosol influence is estimated through cloud correction factor. Aerosols that absorb UV radiation attenuate the surface UV radiation more strongly than non-absorbing aerosols of the same extinction optical depth. Moreover, since these aerosols also attenuate the outgoing satellite-measured radiance, the cloud correction factor that treats these aerosols as purely scattering underestimates their aerosol optical depth (AOD), causing underestimation of LER and overestimation of surface UV irradiance. Therefore, for correction of aerosol absorption, additional information is needed, such as a model-based monthly climatology of aerosol absorption optical depth (AAOD). A correction for absorbing aerosols was proposed almost a decade ago and later implemented in the operational OMI and TROPOMI UV algorithms. In this study, however, we show that there is still room for improvement to better account for the solar zenith angle (SZA) dependence and nonlinearity in the absorbing aerosol attenuation, and as a result we propose an improved correction scheme. There are two main differences between the new proposed correction and the one that is currently operational in OMI and TROPOMI UV algorithms. First, the currently operational correction for absorbing aerosols is a function of AAOD only, while the new correction additionally takes the solar zenith angle dependence into account. Second, the second-order polynomial of the new correction takes the nonlinearity in the correction as a function of AAOD better into account, if compared to the currently operational one, and thus better describes the effect by absorbing aerosols over a larger range of AAOD. To illustrate the potential impact of the new correction in the global UV estimates, we applied the current and new proposed correction for global fields of AAOD from the aerosol climatology currently used in OMI UV algorithm, showing a typical differences of ± 5 %. This new correction is easy to implement operationally using information of solar zenith angle and existing AAOD climatology. [ABSTRACT FROM AUTHOR]

We describe the wavelength calibration of the spectrometer for the scanning of habitable environments with Raman and luminescence for organics and chemicals (SHERLOC) instrument onboard NASA's Perseverance Rover. SHERLOC utilizes deep ultraviolet Raman and fluorescence (DUV R/F) spectroscopy to enable analysis of samples from the Martian surface. SHERLOC employs a 248.6 nm deep ultraviolet laser to generate Raman-scattered photons and native fluorescence emission photons from near-surface material to detect and classify chemical and mineralogical compositions. The collected photons are focused on a charge-coupled device and the data are returned to Earth for analysis. The compact DUV R/F spectrometer has a spectral range from 249.9 nm to 353.6 nm (∼200 cm−1 to 12 000 cm−1) (with a spectral resolution of 0.296 nm (∼40 cm−1)). The compact spectrometer uses a custom design to project a high-resolution Raman spectrum and a low-resolution fluorescence spectrum on a single charge-coupled device. The natural spectral separation enabled by deep ultraviolet excitation enables wavelength separation of the Raman/fluorescence spectra. The SHERLOC spectrometer was designed to optimize the resolution of the Raman spectral region and the wavelength range of the fluorescence region. The resulting illumination on the charge-coupled device is curved, requiring a segmented, nonlinear wavelength calibration in order to understand the mineralogy and chemistry of Martian materials. Graphical Abstract [ABSTRACT FROM AUTHOR]

The nonthermal broadening of spectral lines formed in the solar corona is often used to seek evidence of Alfvén waves propagating in the corona. To have a better understanding of the variation of line widths at different altitudes, we measured the line widths of the strong Fe xii 192.4, 193.5, and 195.1 Å and Fe xiii 202.0 Å in an off-limb southern coronal hole up to 1.5 R⊙ observed by the Extreme Ultraviolet Spectrometer on board the Hinode satellite. We compared our measurements to the predictions from the Alfvén Wave Solar Model (AWSoM) and the SPECTRUM module. We found that the Fe xii and Fe xiii line widths first increase monotonically below 1.1 R⊙ and then keep fluctuating between 1.1 and 1.5 R⊙. The synthetic line widths of Fe xii and Fe xiii below 1.3 R⊙ are notably lower than the observed ones. We found that the emission from a streamer in the line of sight significantly contaminates the coronal hole line profiles even up to 1.5 R⊙ both in observations and simulations. We suggest that either the discrepancy between the observations and simulations is caused by insufficient nonthermal broadening at the streamer in the AWSoM simulation or the observations are less affected by the streamer. Our results emphasize the importance of identifying the origin of the coronal EUV emission in off-limb observations. [ABSTRACT FROM AUTHOR]

The nonthermal broadening of spectral lines formed in the solar corona is often used to seek evidence of Alfvén waves propagating in the corona. To have a better understanding of the variation of line widths at different altitudes, we measured the line widths of the strong Fe xii 192.4, 193.5, and 195.1 Å and Fe xiii 202.0 Å in an off-limb southern coronal hole up to 1.5 R⊙ observed by the Extreme Ultraviolet Spectrometer on board the Hinode satellite. We compared our measurements to the predictions from the Alfvén Wave Solar Model (AWSoM) and the SPECTRUM module. We found that the Fe xii and Fe xiii line widths first increase monotonically below 1.1 R⊙ and then keep fluctuating between 1.1 and 1.5 R⊙. The synthetic line widths of Fe xii and Fe xiii below 1.3 R⊙ are notably lower than the observed ones. We found that the emission from a streamer in the line of sight significantly contaminates the coronal hole line profiles even up to 1.5 R⊙ both in observations and simulations. We suggest that either the discrepancy between the observations and simulations is caused by insufficient nonthermal broadening at the streamer in the AWSoM simulation or the observations are less affected by the streamer. Our results emphasize the importance of identifying the origin of the coronal EUV emission in off-limb observations. [ABSTRACT FROM AUTHOR]