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With the increasing availability of LEDs, researchers in photobiology have easier access to customized light sources. However, the abundance of different light sources poses new challenges for the correct characterization of existing light conditions. The photobiological effect of a light source depends mainly on the number of photons involved and the spectral composition. However, light sources are mainly described by parameters such as radiant flux, dominant or peak wavelength, and correlated color temperature (CCT). Therefore, in this work, chromatic and white light sources were measured for their spectral composition, various characterization parameters were determined, and the resulting photon flux densities were calculated, focusing on dominant versus peak wavelength for chromatic LEDs and the CCT for white LEDs and fluorescent tubes. The use of the dominant wavelength is inappropriate as it is partly outside the actual spectral range. It was also shown that white light sources with the same CCT have significantly different spectral compositions and, therefore, may have different photobiological effects. The results of this work should serve as a basis for life scientists to better compare light sources, to correctly interpret existing parameters, and to describe light conditions in a standardized and comparable way. [ABSTRACT FROM AUTHOR]

Following the rapid growth in accelerator-based light sources research since the mid of 20th century, miscellaneous third generation synchrotron radiation (SR) facilities such as SSRL, APS, ESRF, PETRA-III, and SPring-8 have come into existence. These SR source facilities provide 1020–1025 photons/s/mrad2/mm2/0.1%BW peak brightness within the photon energy range of 10–105 eV. Since different measurement techniques are utilized at X-ray beamlines of SR facilities, many kinds of insertion devices (i.e., undulators and wigglers) and optical components (e.g., high-resolution monochromators, double-crystal monochromators, lenses, mirrors, etc.) are employed for each experimental setup as a matter of course. Under the circumstances, optimization of a synchrotron beamline is a big concern for many scientists to ensure required radiation characteristics (i.e., photon flux, spot size, photon energy, etc.) for dedicated user experiments. In this respect, an in-vacuum hybrid undulator driven by a 6 GeV synchrotron electron beam is optimized using evolutionary algorithms (EA). Finally, it is shown that EA results are well consistent with both the literature and the analytical calculations, resulting in a promising design estimation for beamline scientists. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of the photosynthetically active radiation spectral characteristics influence on the productivity and quality of lettuce and dwarf tomato adapted for protected ground. High pressure sodium lamps and LEDs emitting yellow light, pink light and close to sunlight spectrum were used as test options for plant illumination. Vegetable crops were grown under controlled conditions of intensive lightculture by thin-layer panoponics; the same irradiance was achieved in all variants. Using a light source simulating sunlight with a photosynthetic photon flux of 76 μmol m–2 s–1 in the 400–500 nm range, 130 μmol m–2 s–1 in 500–600 nm and 133 μmol m–2 s–1 at 600–700 nm made it possible to obtain an increase in productivity by 10% for lettuce and by 23% for tomato, and also led to an increase in the content of magnesium and iron in lettuce leaves and a higher content of carbohydrates, vitamin C, crude ash in tomato fruits compared to standard sodium lamps. [ABSTRACT FROM AUTHOR]

The influence of six experimental light sources (lamps) based on LEDs with different emission spectra simulating optical radiation close to solar radiation on the photochemical activity of photosystems (PS) of purple basil leaves and on the redox state of the P700 reaction center was studied. The spectra differed in the photon flux distribution over the main emission spectrum ranges, correlated color temperature (CCT), and general color rendering index (Ra). A comparative analysis of PAM fluorometry parameters resulted in the identification of the spectral regions that ensure more efficient photosynthetic processes in basil leaf cells at stages of technical ripening and flowering. In particular, basil plants grown on a spectrum with a CCT of 5260 K and Ra 98 had a fairly low F0 level, one of the highest Fv/Fm ratios characteristic of plants under nonstressful conditions, one of the highest quantum yields of both PS Y(I) and Y(II), and high electron flow rates. Spectra with CCT 4550 K and Ra 91 and with CCT 2820 K and Ra 81 also looked promising in terms of PAM fluorometry parameters. The spectrum with CCT 2990 and Ra 97 had the worst performance in terms of the studied PSI and PSII parameters. [ABSTRACT FROM AUTHOR]

This article provides an overview of the upgrade of the Swiss Light Source (SLS) synchrotron facility at the Paul Scherrer Institute in Switzerland. The upgrade, known as SLS 2.0, aims to improve the facility's performance by implementing new technologies such as multibend achromats and higher storage-ring energy. The article discusses the X-ray sources at SLS 2.0, including bending magnets and insertion devices, with innovations and upgrades being made for the undulators. The beamlines at SLS 2.0 are also undergoing changes, with upgrades in optics and the addition of new beamlines. The timeline for the project is provided, with full user operation expected after the completion of the upgrades. [Extracted from the article]

The vacuum ultraviolet (VUV) light source derived from the Kr-He discharge is widely used for organic analysis, however the relevant model that greatly facilitates the design of high-performance VUV light sources remains to be developed. This study explores a model for simulating the light intensity of the VUV lamps based on the inductively coupled plasma (ICP) discharge in the low-pressure Kr-He mixture. Two typical ICP based light sources, i.e., a 13.56 MHz VUV lamp with an external coil and a 2.65 MHz VUV lamp with an internal coil, were successfully simulated with the COMSOL Multiphysics software coupled with a fluid model. The rate coefficients of the main reactions involved in the production of VUV radiations from Kr-He plasma were summarized and input in the model. The concentrations of Kr*(3P1) and Kr*(1P1), which are main VUV-generation species, were set as output to evaluate the overall light intensity of the VUV lamp. As a result, the optimal designing parameters (the length and density of the coil and the radius of the lamp) as well as operating parameters (the input power, the pressure inside the lamp, and the mixing ratio of Kr to He) were obtained for the maximum light intensity. The reliability of the model was further verified by comparing the measured photon flux with the simulated concentrations of Kr*(3P1) and Kr*(1P1) as functions of the pressure and mixing ratio of Kr-He mixture, which showed good agreements in variation tends. The model provides a great convenience for the development of ICP based VUV lamp with high light intensity and stability. [ABSTRACT FROM AUTHOR]

The spatio-temporal correlation properties of a pseudo-thermal light source with nano- and microsecond time resolution are studied on the basis of algorithms that take into account the features of a high-speed time-resolving matrix of single-photon detectors. It is shown that the change in the degree of second-order coherence of radiation scattered on a rotating disk with irregularities of different scales can be represented using a nonlinear hyperbolic mapping. The change in coherence during the transition of the generated photon flux from coherent to pseudothermal is studied based on the presented method. [ABSTRACT FROM AUTHOR]

Semiconductors for detecting hard radiation are confronted with considerable problems when operating at high photon fluxes. A perovskite CsPbBr3 single‐crystal detector capable of operating at X‐ray fluxes of up to 1010 photons s−1 mm−2 with beam area ≤ 0.25 mm2 at 58.61 keV for current‐mode X‐ray detection is reported. The spectrometer‐grade melt‐grown CsPbBr3 detectors show a gamma‐ray energy resolution of ~7.5% at 122 keV for 57Co and dark current as low as 4.3 nA (0.5 nA mm−2) at a reverse bias voltage of 200 V (118 V mm−1). The detector is tested at X‐ray energies of 8.2, 10, and 58.61 keV at a synchrotron light source under a reverse bias voltage of up to 1000 V (588 V mm−1). Under a sufficiently high bias voltage and within several hundreds of seconds X‐ray exposure, good photocurrent linearity (goodness of fit R2 > 0.99) and reproducibility are obtained up to a flux of ≈1010 photons s−1 mm−2 at beam area 0.25 mm2 with Lower Limit of Detection of ≈105 photons s−1 mm−2 and Charge Collection Efficiency of ≈100% for 58.61 keV X‐rays. Accordingly, wide application of CsPbBr3 detectors in high‐flux X‐ray detection is anticipated. [ABSTRACT FROM AUTHOR]

Synchrotron radiation based dynamic micro-computed tomography (micro-CT) is a powerful technique available at synchrotron light sources for investigating evolving microstructures. Wet granulation is the most widely used method of producing pharmaceutical granules, precursors to products like capsules and tablets. Granule microstructures are known to influence product performance, so this is an area for potential application of dynamic CT. Here, lactose monohydrate (LMH) was used as a representative powder to demonstrate dynamic CT capabilities. Wet granulation of LMH has been observed to occur on the order of several seconds, which is too fast for lab-based CT scanners to capture the changing internal structures. The superior X-ray photon flux from synchrotron light sources makes sub-second data acquisition possible and well suited for analysis of the wet-granulation process. Moreover, synchrotron radiation based imaging is non-destructive, does not require altering the sample in any way, and can enhance image contrast with phase-retrieval algorithms. Dynamic CT can bring insights to wet granulation, an area of research previously only studied via 2D and/or ex situ techniques. Through efficient dataprocessing strategies, dynamic CT can provide quantitative analysis of how the internal microstructure of an LMH granule evolves during the earliest moments of wet granulation. Here, the results revealed granule consolidation, the evolving porosity, and the influence of aggregates on granule porosity. [ABSTRACT FROM AUTHOR]

We present an apparatus for attosecond transient-absorption spectroscopy (ATAS) featuring soft-X-ray (SXR) supercontinua that extend beyond 450 eV. This instrument combines an attosecond table-top high-harmonic light source with mid-infrared (mid-IR) pulses, both driven by 1.7–1.9 mJ, sub-11 fs pulses centered at 1.76 μ m. A remarkably low timing jitter of ∼ 20 as is achieved through active stabilization of the pump and probe arms of the instrument. A temporal resolution of better than 400 as is demonstrated through ATAS measurements at the argon L 2 , 3 -edges. A spectral resolving power of 1490 is demonstrated through simultaneous absorption measurements at the sulfur L 2 , 3 - and carbon K-edges of OCS. Coupled with its high SXR photon flux, this instrument paves the way to attosecond time-resolved spectroscopy of organic molecules in the gas phase or in aqueous solutions, as well as thin films of advanced materials. Such measurements will advance the studies of complex systems to the electronic time scale. [ABSTRACT FROM AUTHOR]

Coherent extreme ultraviolet (EUV) line emissions can be generated from an atom excited through frustrated tunneling ionization (FTI). The phase variation of the EUV emission in a generation medium along the propagation direction is a critical parameter that determines the phase-matching condition of this new light source. Here we show that the EUV emission sensitively depends on the intensity and phase of a driving laser pulse and the target position. Angle-resolved EUV spectra measured at different target positions and the carrier-envelope phases of the laser pulse exhibit an intensity modulation, showing similar behavior to that of a long-trajectory high harmonic radiation. The four-step model developed for the FTI emission accurately describes the coherent control of the EUV emission. These findings are essential ingredients for developing coherent extreme ultraviolet sources with high photon flux and for utilizing the FTI emission in time-resolved spectroscopy. [ABSTRACT FROM AUTHOR]

Chemical actinometers are a useful tool in photochemistry, which allows to measure the photon flux of a light source to carry out quantitative analysis on photoreactions. The most commonly employed actinometers so far show minor drawbacks, such as difficult data treatment, parasite reactions, low stability or impossible reset. We propose herewith the use of 4,4′-dimethylazobenzene as a chemical actinometer. This compound undergoes a clean and efficient E/Z isomerization, approaching total conversion upon irradiation at 365 nm. Thanks to its properties, it can be used to determine the photon flux in the UV–visible region, with simple experimental methods and data treatment, and with the possibility to be reused after photochemical or thermal reset. [ABSTRACT FROM AUTHOR]

Basing on the slant Compton scattering of 10640 nm photons from a 100 W CO 2 laser on 3.5 GeV electrons from the Shanghai Light Source, the Shanghai Laser Electron Gamma Source (SLEGS) produces gamma-ray in the energy range of 0.66 MeV–21.7 MeV and flux of 105–107 photons/s. A Gamma Modulation System (GMS) composed of the collimators, attenuator, beam spot imaging(MiniPIX) and flux monitor(LaBr 3 detector) was developed to ensure producing bandwidth-variable quasi-monochromatic gamma-ray with a variable-flux at same time. Using the GMS, variable-flux quasi-monochromatic gamma-ray beams with a best bandwidth of 10% in the 90 ∘ slant-scattering and 4% in back-scattering were obtained respectively. We report on the performance of the GMS and results of gamma-ray beam modulating measurement with GMS at SLEGS. • SLEGS is a medium energy resolution slant-scattering beamline. • This article provides beam parameters for users on SLEGS. • The Gamma Modulation System(GMS) is effective in modulating gamma-ray beams. • Using the GMS, 4%–10% energy resolution can be obtained. • Flux of 105-107 photons/s can be obtained with 5 W laser power. [ABSTRACT FROM AUTHOR]

We propose a practical method for radiometrically calibrating cameras using widely available gaseous tritium light sources (betalights). Along with the gain (conversion factor) and read noise level, the predictable photon flux of the source allows us to gauge the quantum efficiency. The design is easily reproducible with a 3D printer (three-dimensional printer) and three inexpensive parts. Suitable for common image sensors, we believe that the method has the potential to be a useful tool in microscopy facilities and optical laboratories alike. [ABSTRACT FROM AUTHOR]

The CoSAXS beamline at the MAX IV Laboratory is a modern multi‐purpose (coherent) small‐angle X‐ray scattering (CoSAXS) instrument, designed to provide intense and optionally coherent illumination at the sample position, enabling coherent imaging and speckle contrast techniques. X‐ray tracing simulations used to design the beamline optics have predicted a total photon flux of 1012–1013 photons s−1 and a degree of coherence of up to 10% at 7.1 keV. The normalized degree of coherence and the coherent flux of this instrument were experimentally determined using the separability of a ptychographic reconstruction into multiple mutually incoherent modes and thus the Coherence in the name CoSAXS was verified. How the beamline can be used both for coherent imaging and XPCS measurements, which both heavily rely on the degree of coherence of the beam, was demonstrated. These results are the first experimental quantification of coherence properties in a SAXS instrument at a fourth‐generation synchrotron light source. [ABSTRACT FROM AUTHOR]

Continuous-flow microstructured technologies are now recognized as promising alternatives to batch processing for organic photochemistry, especially when light emitting diodes (LEDs) are employed as light sources. To evaluate and optimize productivity and energetic efficiency, the knowledge of the incident photon flux density is crucial. In this context, the objectives of the present work are dual: first, to transfer the classical actinometry method with Reinecke's salt to a continuous-flow LED-driven spiral-shaped reactor and second, to propose a revised one-dimensional equivalent model for the accurate determination of the incident photon flux density in this microreactor. Experimental measurements were carried out under controlled conditions. The effects of the spectral domain and radiant power emitted, the tubing length, the presence of gas-liquid Taylor flow, and the material of the support plate were especially investigated. An expression was established for the revised one-dimensional Cartesian model, taking into account the diffuse emission of the LED array and the reflection induced by the material of the plate in which the tubing was inserted (i.e. the reflection by the backside of the microreactor wall). In this way, the incident photon flux density could be estimated with an acceptable level of accuracy, which was not the case if the usual 1D model was applied (collimated emission and no reflection). [ABSTRACT FROM AUTHOR]

Oxygenic photosynthesis is the most important biochemical process in Earth biosphere and likely very common on other habitable terrestrial planets, given the general availability of its input chemical ingredients and of light as source of energy. It is therefore important to evaluate the effective possibility of oxygenic photosynthesis on planets around stars as a function of their spectral type and the planet–star separation. We aim at estimating the photon flux, the exergy, and the exergetic efficiency of the radiation in the wavelength range useful for the oxygenic photosynthesis as a function of the host star effective temperature and planet–star separation. We compute analytically these quantities and compare our results with the estimates for the small sample of known Earth-like planets. We find that exergy is an increasing function of the star effective temperature, within the range 2600–7200 K. It depends both on the star–planet separation and the star effective temperature. Biospheres on exoplanets around cool stars might be generally light-limited. So far, we have not observed terrestrial planets comparable to Earth in terms of useful photon flux, exergy, and exergetic efficiency. [ABSTRACT FROM AUTHOR]

We measured wavelength‐resolved ultraviolet (UV) irradiance in multiple indoor environments and quantified the effects of variables such as light source, solar angles, cloud cover, window type, and electric light color temperature on indoor photon fluxes. The majority of the 77 windows and window samples investigated completely attenuated sunlight at wavelengths shorter than 320 nm; despite variations among individual windows leading to differences in indoor HONO photolysis rate constants (JHONO) and local hydroxyl radical (OH) concentrations of up to a factor of 50, wavelength‐resolved transmittance was similar between windows in residential and non‐residential buildings. We report mathematical relationships that predict indoor solar UV irradiance as a function of solar zenith angle, incident angle of sunlight on windows, and distance from windows and surfaces for direct and diffuse sunlight. Using these relationships, we predict elevated indoor steady‐state OH concentrations (0.80–7.4 × 106 molec cm−3) under illumination by direct and diffuse sunlight and fluorescent tubes near windows or light sources. However, elevated OH concentrations at 1 m from the source are only predicted under direct sunlight. We predict that reflections from indoor surfaces will have minor contributions to room‐averaged indoor UV irradiance. These results may improve parameterization of indoor chemistry models. [ABSTRACT FROM AUTHOR]

A new diffraction beamline for materials science has been built at the Canadian Light Source synchrotron. The X‐ray source is an in‐vacuum wiggler with a 2.5 T peak magnetic field at 5.2 mm gap. The optical configuration includes a toroidal mirror, a single side‐bounce Bragg monochromator, and a cylindrical mirror, producing a sub‐150 µm vertical × 500 µm horizontal focused beam with a photon energy range of 7–22 keV and a flux of 1012 photons per second at the sample position. Three endstations are currently open to general users, and the techniques available include high‐resolution powder diffraction, small molecule crystallography, X‐ray reflectivity, in situ rapid thermal annealing, and SAXS/WAXS. The beamline design parameters, calculated and measured performance, and initial experimental results are presented to demonstrate the capabilities for materials science. [ABSTRACT FROM AUTHOR]

Light-emitting diodes (LEDs) have recently been widely used as light sources for the cultivation of plants in controlled environments. However, before LEDs can be used as the sole light source, it is imperative that soybean (Glycine max) response to light quality be well characterized. The objective of the present work was to investigate how soybean seedlings respond to different blue (B) and red (R) photon flux ratios (PFR) using LEDs. Light treatments were comprised of 170 ± 5 μmol m−2 s−1 photosynthetic photon flux density with B:R ratios of 0B:100R%, 10B:90R%, 25B:75R%, 50B:50R%, 80B:20R%, 90B:10R%, and 100B:0R%. Our results suggest that with the increase in B PFR from 0 to 90%, both plant height and specific leaf area inclined to decline while stem diameter gradually increased. The plants exposed to 80B:20R% showed unexpectedly greater total root length, root surface area, root volume, number of root tip, plant dry mass, leaf dry mass, root dry mass, leaf mass fraction and root mass fraction than plants exposed to all other treatments. Plants grown with 0B:100R% had the highest content of chlorophyll b (Chl b) and content of total chlorophyll [Chl (a + b)] but possessed the lowest ratio of the content of chlorophyll a to the content of chlorophyll b (Chl a/b). Plants grown with R alone also showed the lowest chlorophyll fluorescent parameters. The light-saturated CO2 assimilation rate (Asat) and the light-saturated stomatal conductance (gssat) for 0B:100R% were, respectively, 64.85% and 203.23% lower than those for 80B:20R%. However, plants grown with sole R accumulated higher soluble sugar and starch content during the daytime. Collectively, our results suggest that compared to R- or B-LED alone, an appropriate combination of R and B promotes plant growth and photosynthetic performance for soybean. [ABSTRACT FROM AUTHOR]

Soft X‐rays excite the inner shells of materials more efficiently than any other form of light. The investigation of synchrotron radiation (SR) processes using inner‐shell excitation requires the beamline to supply a single‐color and high‐photon‐flux light in the soft X‐ray region. A new integrated computing multi‐layered‐mirror (MLM) monochromator was installed at beamline 07A (BL07A) of NewSUBARU, which has a 3 m undulator as a light source for irradiation experiments with high‐photon‐flux monochromatic light. The MLM monochromator has a high reflectivity index in the soft X‐ray region; it eliminates unnecessary harmonic light from the undulator and lowers the temperature of the irradiated sample surfaces. The monochromator can be operated in a high vacuum, and three different mirror pairs are available for different experimental energy ranges; they can be exchanged without exposing the monochromator to the atmosphere. Measurements of the photon current of a photodiode on the sample stage indicated that the photon flux of the monochromatic beam was more than 1014 photons s−1 cm−2 in the energy range 80–400 eV and 1013 photons s−1 cm−2 in the energy range 400–800 eV. Thus, BL07A is capable of performing SR‐stimulated process experiments. [ABSTRACT FROM AUTHOR]

The cost of providing lighting in greenhouses and plant factories can be high. In the case of variable electricity prices, providing most of the light when electricity prices are low can reduce costs. However, it is not clear how plants respond to the resulting fluctuating light levels. We hypothesized that plants that receive a constant photosynthetic photon flux density (PPFD) will produce more biomass than those grown under fluctuating light levels. To understand potential growth reductions caused by fluctuating light levels, we quantified the effects of fluctuating PPFD on the photosynthetic physiology, morphology, and growth of 'Little Gem' and 'Green Salad Bowl' lettuce. Plants were grown in a growth chamber with dimmable white LED bars, alternating between high and low PPFDs every 15 min. The PPFDs were ∼400/0, 360/40, 320/80, 280/120, 240/160, and 200/200 μmol⋅m−2⋅s–1, with a photoperiod of 16 h and a DLI of ∼11.5 mol⋅m−2⋅day–1 in all treatments. CO2 was ∼800 μmol⋅mol–1. Plants in the 400/0 μmol⋅m−2⋅s–1 treatment had ∼69% lower An,30 (net assimilation averaged over 15 min at high and 15 min at low PPFD) than plants grown at a PPFD of 320/80 μmol⋅m−2⋅s–1 (or treatments with smaller PPFD fluctuations). The low An,30 in the 400/0, and to a lesser extent the 360/40 μmol⋅m−2⋅s–1 treatment was caused by low net assimilation at 360 and 400 μmol⋅m−2⋅s–1. Plants grown at 400/0 μmol⋅m−2⋅s–1 also had fewer leaves and lower chlorophyll content compared to those in other treatments. The four treatments with the smallest PPFD fluctuations produced plants with similar numbers of leaves, chlorophyll content, specific leaf area (SLA), dry mass, and leaf area. Chlorophyll content, An,30, and dry mass were positively correlated with each other. Our results show that lettuce tolerates a wide range of fluctuating PPFD without negative effects on growth and development. However, when fluctuations in PPFD are extreme (400/0 or 360/40 μmol⋅m−2⋅s–1), chlorophyll levels and An,30 are low, which can explain the low poor growth in these treatments. The ability of lettuce to tolerate a wide range of fluctuating light levels suggests that PPFD can be adjusted in response to variable electricity pricing. [ABSTRACT FROM AUTHOR]

Purpose: X‐ray microbeam radiation therapy is a preclinical concept for tumor treatment promising tissue sparing and enhanced tumor control. With its spatially separated, periodic micrometer‐sized pattern, this method requires a high dose rate and a collimated beam typically available at large synchrotron radiation facilities. To treat small animals with microbeams in a laboratory‐sized environment, we developed a dedicated irradiation system at the Munich Compact Light Source (MuCLS). Methods: A specially made beam collimation optic allows to increase x‐ray fluence rate at the position of the target. Monte Carlo simulations and measurements were conducted for accurate microbeam dosimetry. The dose during irradiation is determined by a calibrated flux monitoring system. Moreover, a positioning system including mouse monitoring was built. Results: We successfully commissioned the in vivo microbeam irradiation system for an exemplary xenograft tumor model in the mouse ear. By beam collimation, a dose rate of up to 5.3 Gy/min at 25 keV was achieved. Microbeam irradiations using a tungsten collimator with 50 μm slit size and 350 μm center‐to‐center spacing were performed at a mean dose rate of 0.6 Gy/min showing a high peak‐to‐valley dose ratio of about 200 in the mouse ear. The maximum circular field size of 3.5 mm in diameter can be enlarged using field patching. Conclusions: This study shows that we can perform in vivo microbeam experiments at the MuCLS with a dedicated dosimetry and positioning system to advance this promising radiation therapy method at commercially available compact microbeam sources. Peak doses of up to 100 Gy per treatment seem feasible considering a recent upgrade for higher photon flux. The system can be adapted for tumor treatment in different animal models, for example, in the hind leg. [ABSTRACT FROM AUTHOR]

XIDer is a 2D pixelated hybrid X-ray detector that is supposed to act as a multi-purpose platform for diffraction experiments at fourth-generation high-energy synchrotron light sources like the Extremely Brilliant Source of the European Synchrotron Radiation Facility (ESRF-EBS). As such it needs to tackle a wide variety of requirements. These include x-ray energies of 30 keV to 100 keV imposing the utilisation of high-Z sensors, a wide dynamic range from single photons to fluxes of 1 × 109 photons pixel−1 s−1 and expected raw data rates up to the order of TB s−1 in the final detector design. As a result, XIDer's readout ASIC has to provide smart and flexible ways for on-chip data pre-processing to reduce the output data rate to manageable sizes. This article focusses on introducing the ASIC's novel and unique data-handling concepts like the custom-designed telegram protocol followed by the presentation of exemplary configurations and use cases. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of different culture conditions on the vegetative growth of a new species, Haematococcus alpinus (strain LCR‐CC‐261f) using airlift photobioreactors. The influence of culture medium, aeration rates, CO2 concentration in air‐gas mixture, temperature, light intensities, and wavelengths were investigated to achieve sustainable high cell density cultures. Growth parameters were determined by fitting the data to a form of the logistic equation that included a lag phase. The shear‐sensitive vegetative cells favored lower aeration rates in the photobioreactors. MLA medium increased to 40 mM nitrate produced high density cultures. Temperatures between 12°C and 18°C, 3% (v/v) CO2 concentration and a narrow photon flux density ranging between 37 and 48 μmol photons · m−2 · s−1 were best suited for growth. The wavelength of the light source also impacted growth and a high cell density of 9.6 × 105 cells · mL−1 was achieved using a mixture of red and blue compared to warm white, red, or blue LEDs. [ABSTRACT FROM AUTHOR]

Modern photon‐counting pixel detectors have enabled a revolution in applications at synchrotron light sources and beyond in the last decade. One of the limitations of the current detectors is their reduced counting linearity or even paralysis at high counting rates, due to dead‐time which results in photon pile‐up. Existing dead‐time and pile‐up models fail to reproduce the complexity of dead‐time effects on photon‐counting, resulting in empirical calibrations for particular detectors at best, imprecise linearization methods, or no linearization. This problem will increase in the future as many synchrotron light sources plan significant brilliance upgrades and free‐electron lasers plan moving to a quasi‐continuous operation mode. Presented here are the first models that use the actual behavior of the analog pre‐amplifiers in spectroscopic photon‐counting pixel detectors with constant current discharge (e.g. the Medipix and CPix families of detectors) to deduce more accurate analytical models and optimal linearization methods. In particular, for detectors with at least two counters per pixel, the need for calibration, or previous knowledge of the detector and beam parameters (dead‐time, integration time, large sets of synchrotron filling patterns), is completely eliminated. This is summarized in several models of increasing complexity and accuracy. Finally, a general empirical approach is presented, applicable to any particular cases where the analytical approach is not sufficiently precise. [ABSTRACT FROM AUTHOR]

Time-resolved imaging allows revealing the interaction mechanisms in the microcosm of both inorganic and biological objects. While X-ray microscopy has proven its advantages for resolving objects beyond what can be achieved using optical microscopes, dynamic studies using full-field imaging at the nanometer scale are still in their infancy. In this perspective, we present the current state of the art techniques for full-field imaging in the extreme-ultraviolet- and soft X-ray-regime which are suitable for single exposure applications as they are paramount for studying dynamics in nanoscale systems. We evaluate the performance of currently available table-top sources, with special emphasis on applications, photon flux, and coherence. Examples for applications of single shot imaging in physics, biology, and industrial applications are discussed. [ABSTRACT FROM AUTHOR]

The cultivation of Chlorella sp., the most abundant microalga in the Persian Gulf, took place in a novel pyramid photobioreactor (PBR), a modified version of plate PBR, consisting of four completely separate equal-volume chambers. In this study we used two light sources incident in each chamber: light-emitting diode (LED) at various wavelengths (red, white and blue) of 108 µmol/(m2·s) photosynthetic photon flux density as internal lighting, and the same photon flux density for external white lighting. PBR served to study the effects of light sources on chlorophyll a production, maximum specific growth rate (µmax), biomass productivity rate (rp) and photon performance. The results showed that the highest chlorophyll a production was obtained under red LED illumination. The highest values for rp, µmax and photon performance were obtained under white light. [ABSTRACT FROM AUTHOR]

Traditionally, the general photochemical rate equation could be integrated only at two limits (high concentration and low concentration). In this paper, the general photochemical equation has been integrated to yield a master equation that is valid for any chromophore concentration. Hence, in future, data for all concentrations can be utilized in deriving the incident photon flux and/or the quantum yield for a photochemical reaction. Unfortunately, the master equation can only be used for monochromatic light sources. [ABSTRACT FROM AUTHOR]

In this paper, a new beamline optical system design method is reported in which the calculation of synchrotron radiation source flux distribution, monochromator spectral resolving power, mirror reflectance and grating diffraction efficiency are integrated together in one program to evaluate the whole beamline optical system performance. We demonstrate the advantage of this method by applying it to the Surface Physics beamline at Hefei Light Source to find out better optical system parameters. By using this method, a higher photon flux with the same spectral resolving power than the original design is achieved. The integrated optical system design method provides a great promising application in the beamline optical design and optimization in the future. [ABSTRACT FROM AUTHOR]

Photochemistry is a largely unconsidered potential source of reactive species such as hydroxyl and peroxy radicals (OH and HO2, "HOx") indoors. We present measured wavelength-resolved photon fluxes and distance dependences of indoor light sources including halogen, incandescent, and compact fluorescent lights (CFL) commonly used in residential buildings; fluorescent tubes common in industrial and commercial settings; and sunlight entering buildings through windows. We use these measurements to predict indoor HOx production rates from the photolysis of nitrous acid (HONO), hydrogen peroxide (H2O2), ozone (O3), formaldehyde (HCHO), and acetaldehyde (CH3CHO). Our results suggest that while most lamps can photolyze these molecules, only sunlight and fluorescent tubes will be important to room-averaged indoor HOx levels due to the strong distance dependence of the fluxes from compact bulbs. Under ambient conditions, we predict that sunlight and fluorescent lights will photolyze HONO to form OH at rates of 106-107 molecules cm-3 s-1, and that fluorescent lights will photolyze HCHO to form HO2 at rates of ~106 molecules cm-3 s-1; rates could be 2 orders of magnitude higher under high precursor concentrations. Ozone and H2O2 will not be important photochemical OH sources under most conditions, and CH3CHO will generally increase HO2 production rates only slightly. We also calculated photolysis rate constants for nitrogen dioxide (NO2) and nitrate radicals (NO3) in the presence of the different light sources. Photolysis is not likely an important fate for NO3 indoors, but NO2 photolysis could be an important source of indoor O3. [ABSTRACT FROM AUTHOR]

Photochemical reactions have become a widely studied topic in the past decade, as they are employed in a wide range of processes and are recognized to be a fundamental tool in the field of sustainable chemistry. Moreover, in recent years there is an increasing interest in turning discontinuous photochemical processes into continuous ones, since continuous processes can ensure better results in terms of productivity and selectivity. In this work, a novel static mixer useful to reach a plug-flow behaviour inside a square-based reactor, while not obstructing the photon flux coming from the light sources, was designed. Through RANS based CFD simulations, the residence time distribution of molecules inside the reactor was evaluated. Moreover, the effect of both absorption and scattering phenomena, which play a major role in photochemical reactions, was assessed. Finally, a case study was considered and the photochemical degradation of 2-hydroxybenzoic acid (2-HBA) was simulated. The conversion obtained in the reactor equipped with SMs was compared to an empty reactor, finding that the degradation efficiency is doubled. [Display omitted] • A novel static mixer was designed. • Mixing length and residence time distribution (RTD) are analysed through CFD simulations. • A photochemical mesoreactor equipped with SMs is simulated through CFD. • A complete light obstruction analysis was done. • Validation with 2-HBA photodegradation in a photochemical mesoreactor equipped with SMs. [ABSTRACT FROM AUTHOR]

The article reviews the "LightSyn Lighthouse" specialized photochemistry reaction system, from Asynt; and the "PhotoSyn" photoreactor from Uniqsis.

In the last five years, a strong experimental and theoretical activity has been dedicated to the study of inner-shell double photoionization. Almost simultaneously, between 2009 and 2011, different experiments were performed using two different light sources: well established third generation synchrotron light sources that exist for more than two decades and recently developed x-ray free electron lasers (X-FEL) that provide brightness of about 10 orders of magnitude higher. The high photon flux of X-FEL has made possible the successive absorption of many x-ray photons by inner-shell electrons in femtosecond timescale. The possibility to create multiple inner-shell vacancies with this new X-FEL light source has resuscitated “prophetic” 25 years old calculations by Cederbaum et al. [1,2] concerning double K-shell ionization that could be of great interest when conventional Electron Spectroscopy for Chemical Analysis (ESCA) finds some limitations. As a feedback, this has stimulated new theoretical developments. On the other hand, it was considered practically out of reach to observe such states with conventional third generation synchrotron light sources due to the very weak probability to eject two inner-shell electrons by a single photon when the dominant process, that could mask everything else, is single inner-shell ionization. However, due to the development of very efficient detection techniques, it was also possible to perform spectroscopy of double core-hole states with excellent accuracy using third generation synchrotron sources. In this paper we give an outlook on the basis of recently published results, of the complementarity of these light sources for double core-hole spectroscopy. Some new developments and results are also presented with a prospective of what could be done in the future with the technical breakthrough that will be necessary to improve our further understanding of chemical analysis. [ABSTRACT FROM AUTHOR]

The study of the interaction of light with photochemical and photobiological systems requires an accurate assessment of the incident photon flux. The determination of photon fluxes for various light sources (monochromatic and polychromatic) has an inherent advantage since the use of standard quantum yields for the actinometer assures that the photon flux has been calculated against accepted standards. Alternatively, if the photon flux is known, chemical actinometry can be used to determine quantum yields. This study illustrates how incident photon fluxes and quantum yields can be estimated for photochemical and photobiological systems. First, an example is developed to calibrate a spectroradiometer using a low-pressure (LP) UV lamp using either the ferrioxalate or iodide/iodate actinometers. The Calibration Factors (CFs) (defined as the ratio between the actinometer and the spectroradiometer) agreed very well, demonstrating the consistency of quantum yields between well-researched actinometers. Second, since UV-LEDs have a bandwidth almost twice that of LP lamps, should UV-LEDs be treated as monochromatic or polychromatic light sources? Results showed no significant differences between the monochromatic analysis and the polychromatic analysis. Third, the uridine quantum yield is 0.025 ± 0.001 over the 254–279 nm wavelength range, independent of these wavelengths. [Display omitted] • UV-LED at 279 nm can be considered as a quasi-monochromatic UV source. • For UV-LEDs, a monochromatic analysis using only the peak wavelength is sufficient. • Master equation obtains accurate quantum yield or incident photon flux. • Master equation is valid for all initial concentration ranges for the actinometers. • Uridine QY is 0.025 ± 0.001 and wavelength-independent between 254 and 279 nm. [ABSTRACT FROM AUTHOR]

• Good agreement of theoretical model with experimental results for hollow-core gas cells. • HHG efficiency of 10−8–10−7 in cut-off region with orders higher than the 51st. • Stable operation of HHG light source for hours. • HHG system for various applications including actinic EUV mask inspection. We have developed a coherent and compact extreme-ultraviolet light source based on phase-matched high harmonic generation by using a hollow-core gas cell that can be easily aligned and maintain long stability. The gas cell consists of three bodies to minimize gas leakage and maintain stable vacuum. The photon flux was calculated considering the dependence of the gas number density and the pressure on the radii of the hollow core and the hole in the Al plates on both sides of the gas cell, which showed good coincidence with the experimental values. The photon flux is 2 × 1010 photons s−1 near 13.5 nm (91.5 eV) within 10 nm bandwidth. Also, the compact extreme-ultraviolet light source is found to operate stably for hours, which is suitable for practical applications such as metrology and inspection for extreme-ultraviolet mask, spectroscopy, holography, microscopy, etc. [ABSTRACT FROM AUTHOR]

[Display omitted] • A scalable Light-Diffusing Photochemical Reactor (LDPR) was developed. • LDPR decouples photon and heat to improve thermal management. • α-Amino arylation and C(sp2)–N cross-coupling reactions were demonstrated in LDPR. • Achieved a 10-gram scale photochemical synthesis via a hybrid scale-up strategy. In the last decade, photoredox catalysis has received a remarkable attention for its unique reactivity for synthesizing fine chemicals and active pharmaceutical ingredients. However, the coupled photon and heat generation of light sources create challenges for achieving a proper heat management of photochemical reactors, thus inhibiting large-scale applications. In this work, we proposed a strategy to decouple photon and heat using light guide plate (LGP) technology, and accordingly designed a continuous light-diffusing photochemical reactor (LDPR). In LDPR, the photons emitted from the edge light source are distributed uniformly on the top surface of LGP where the fluidic channels are located. This configuration isolates heat generation location from where photons are utilized, benefiting the heat management of the reaction zone. The photon flux of LDPR was characterized with a chemical actinometry method. Two important photocatalytic bond-forming reactions, α-amino arylation and C(sp2)–N cross-coupling, were demonstrated in LDPR with high efficiency. To show the scalability of LDPR, we increased the throughput via a hybrid strategy of scaling-up and scaling-out, achieving a continuous 10-gram synthesis of an α-amino arylation product. [ABSTRACT FROM AUTHOR]

Photosynthesis (Pn) and photomorphogenesis (Pm) are affected by light quality, light intensity and photoperiod. Although blue light ( BL) is necessary for normal development, it is less efficient in driving Pn than other wavelengths of photosynthetically active radiation. The effects of BL on Pm are highly species dependent. Here we report the interacting effects of BL and photosynthetic photon flux ( PPF) on growth and development of lettuce, radish and pepper. We used light-emitting diode ( LED) arrays to provide BL fractions from 11% to 28% under broad-spectrum white LEDs, and from 0.3% to 92% under monochromatic LEDs. All treatments were replicated three times at each of two PPFs (200 and 500 μmol m−2 s−1). Other than light quality, environmental conditions were uniformly maintained across chambers. Regardless of PPF, BL was necessary to prevent shade-avoidance responses in radish and lettuce. For lettuce and radish, increasing BL reduced stem length, and for both species, there were significant interactions of BL with PPF for leaf expansion. Increasing BL reduced petiole length in radish and flower number in pepper. BL minimally affected pepper growth and other developmental parameters. Pepper seedlings were more photobiologically sensitive than older plants. Surprisingly, there were few interactions between monochromatic and broad-spectrum light sources. [ABSTRACT FROM AUTHOR]

The fundamental advantage of soft-X-ray ARPES (SX-ARPES) with photon energies around 1 keV compared to the conventional vacuum-ultraviolet ARPES (VUV-ARPES) is an increase of the photoelectron escape depth. This enhances the bulk sensitivity of the ARPES experiment as well as enables access to buried systems such as interfaces, heterostructures, and impurities. This advantage combines with resolution in three-dimensional (3D) momentumk, which, on the other hand, degrades upon further increase of energy into the hard-X-ray range. The main challenge of SX-ARPES is the valence band (VB) photoemission cross-section decreasing by a few orders of magnitude compared to the VUV-ARPES energy range. This problem can only be overpowered with advanced synchrotron radiation instrumentation delivering high photon flux. In this article, after a recap of the main virtues and current challenges of SX-ARPES, we report on the recent instrumental progress at the Swiss Light Source (SLS), where a new SX-ARPES facility was installed at the Advanced Resonant Spectroscopies (ADRESS) beamline. The high photon flux above 1013photons/s/0.01%BW delivered by this beamline, combined with the optimized endstation geometry, has allowed us to break through the cross-section problem and, furthermore, push the applications of SX-ARPES from bulk materials to extremely photon-hungry cases of buried systems. Complementing the recent review of the whole field of soft- and hard-X-ray ARPES published in this magazine [1], we here focus on the recent SX-ARPES applications emerging with the advanced instrumentation of the SLS. [ABSTRACT FROM AUTHOR]

• Cos lettuce was grown under light transmitted through a green or red QD sheet. • Differences in growth were only caused by the light environment. • No special effects of QD sheets on plants were observed. • A high-efficiency QD light source may be used for plant cultivation in the future. The aims of this study were to cultivate cos lettuce (Lactuca sativa L. cv. Cos Lettuce) using quantum dot (QD) sheets for wave conversion and to clarify the advantages and disadvantages of this technique for plant cultivation with artificial lighting. Blue LED light was wavelength-converted to green (G-QD) or red (R-QD) light by QD sheets and used for cultivating cos lettuce. Then, lighting with spectral photon flux density distributions similar to those of G-QD and R-QD was designed using green or red LED and blue LED (G-LED and R-LED), respectively, and used for cultivating cos lettuce. Plant growth at 14 days after treatment revealed that the shoot fresh weight was greater under G-QD compared with G-LED, perhaps because the amount of integrated light reception was greater in G-QD owing to the difference in the photosynthetic photon flux density's spatial distribution. Plants showed similar growth levels and morphologies under R-QD and R-LED lights. Plant growth is affected by the light environment, such as spectral photon flux density distributions and its vector field, regardless of the light source. However, the prototype QD sheets used in the present study had low conversion efficiencies and wide directivity angles. If QD products are developed that utilize the advantages of high monochromaticity and long life for plant cultivation at low costs, then they may become widely used. [ABSTRACT FROM AUTHOR]

X-ray computer tomography is a powerful method for nondestructive investigations in many fields. Three-dimensional images of internal structure are reconstructed from a sequence of two-dimensional projections. The polychromatic high density photon flux of modern synchrotron light sources offer hard X-ray imaging with spatio-temporal resolution up to the micrometer and micrometers range. Existing indirect X-ray image detection systems can be adapted for fast image acquisition by high-speed visible-light cameras. In this paper, we present a platform for custom high-speed CMOS cameras with embedded field-programmable gate array (FPGA) processing. This modular system is characterized by a high-throughput PCI Express (PCIe) interface and efficient communication blocks. It has been used to develop a novel architecture for a self-event trigger that increases the effective image frame rate and reduces the amount of received data. Thanks to a low-noise design, high frame rates in the kilohertz range, and high-throughput data transfer, this camera is well suited for ultrafast synchrotron-based X-ray radiography and tomography. The camera setup is accomplished by high-throughput Linux drivers and a seamless integration in our GPU computing framework. [ABSTRACT FROM AUTHOR]

We report on the full control of the optical radiation pressure at fixed photon flux and incident angle by the photon spin. This is done by using transparent chiral liquid crystal droplets that enable a strong coupling between the linear and angular degrees of freedom of a light field. From these results, we anticipate optical sorting of particles with different chirality as well as novel optical trapping and micromanipulation strategies. [ABSTRACT FROM AUTHOR]

At BESSY II a confocal plane grating spectrometer for resonant inelastic X-ray scattering (RIXS) is currently under commissioning. The new endstation operates with a source size of 4×1μm2 provided by its dedicated beamline. The RIXS-spectrometer covers an energy range from 50eV to 1000eV, providing a resolving power E/ΔE of 5000–15,000. The beamline allows full polarization control and gives a photon flux of up to 7×1014 photons/s/0.1A/0.1%bandwidth by offering a resolving power E/ΔE of 4000–12,000. [ABSTRACT FROM AUTHOR]

Plants will be an important component of future long-term space missions. Lighting systems for growing plants will need to be lightweight, reliable, and durable, and light-emitting diodes (LEDs) have these characteristics. Previous studies demonstrated that the combination of red and blue light was an effective light source for several crops. Yet the appearance of plants under red and blue lighting is purplish gray making visual assessment of any problems difficult. The addition of green light would make the plant leave appear green and normal similar to a natural setting under white light and may also offer a psychological benefit to the crew. Green supplemental lighting could also offer benefits, since green light can better penetrate the plant canopy and potentially increase plant growth by increasing photosynthesis from the leaves in the lower canopy. In this study, four light sources were tested: 1) red and blue LEDs (RB), 2) red and blue LEDs with green fluorescent lamps (RGB), 3) green fluorescent lamps (GF), and 4) cool-white fluorescent lamps (CWF), that provided 0%, 24%, 86%, and 51% of the total PPF in the green region of the spectrum, respectively. The addition of 24% green light (500 to 600 nm) to red and blue LEDs (RGB treatment) enhanced plant growth. The RGB treatment plants produced more biomass than the plants grown under the cool-white fluorescent lamps (CWF treatment), a commonly tested light source used as a broad-spectrum control. [ABSTRACT FROM AUTHOR]