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Mitochondria are dynamic organelles that change morphology to adapt to cellular energetic demands under both physiological and stress conditions. Cardiomyopathies and neuronal disorders are associated with structure-related dysfunction in mitochondria, but three-dimensional characterizations of the organelles are still lacking. In this study, we combined high-resolution imaging and 3D electron density information provided by cryo-soft X-ray tomography to characterize mitochondria cristae morphology isolated from murine. Using the linear attenuation coefficient, the mitochondria were identified (0.247 ± 0.04 µm−1) presenting average dimensions of 0.90 ± 0.20 µm in length and 0.63 ± 0.12 µm in width. The internal mitochondria structure was successfully identified by reaching up the limit of spatial resolution of 35 nm. The internal mitochondrial membranes invagination (cristae) complexity was calculated by the mitochondrial complexity index (MCI) providing quantitative and morphological information of mitochondria larger than 0.90 mm in length. The segmentation to visualize the cristae invaginations into the mitochondrial matrix was possible in mitochondria with MCI ≥ 7. Altogether, we demonstrated that the MCI is a valuable quantitative morphological parameter to evaluate cristae modelling and can be applied to compare healthy and disease state associated to mitochondria morphology.

We present observations of four bright stars observed with the AstroSat Soft X-ray Telescope (SXT). Visible light from bright stars like these can leak through the very thin filter in front of the CCD in the focal plane CCD camera of the SXT and thus making the extraction of X-ray events difficult. Here, we show how to extract the X-ray events without contamination by the visible light. The procedure applied to four bright stars here demonstrates how reliable X-ray information can be derived in such cases. The sample of bright stars studied here consists of two A spectral types (HIP 19265, HIP 88580), one G/K Giant (Capella), and a nearby M-type dwarf (HIP 23309). No X-ray emission is observed from the A-type stars, as expected. X-ray spectra of Capella and HIP 23309 are derived and modeled here, and compared with the previous X-ray observations of these stars to show the reliability of the method used. We find that optical light can start to leak in the very soft energy bands below 0.5 keV for stars with V=8 mag. In the process, we present the first X-ray spectrum of HIP 23309., To appear in the Journal of Astrophysics and Astronomy; 8 pages, 7 figures

A novel ultrahigh-resolution x-ray microscope achieves 8-nm spatial resolution and accurately maps chemistry in nanomaterials., The analysis of chemical states and morphology in nanomaterials is central to many areas of science. We address this need with an ultrahigh-resolution scanning transmission soft x-ray microscope. Our instrument provides multiple analysis tools in a compact assembly and can achieve few-nanometer spatial resolution and high chemical sensitivity via x-ray ptychography and conventional scanning microscopy. A novel scanning mechanism, coupled to advanced x-ray detectors, a high-brightness x-ray source, and high-performance computing for analysis provide a revolutionary step forward in terms of imaging speed and resolution. We present x-ray microscopy with 8-nm full-period spatial resolution and use this capability in conjunction with operando sample environments and cryogenic imaging, which are now routinely available. Our multimodal approach will find wide use across many fields of science and facilitate correlative analysis of materials with other types of probes.

New free electron lasers, such as SLAC's LCLS-II, will provide unique scientific imaging opportunities with soft xrays from 250eV-1.5KeV. In order to fully utilize these facilities, we need to develop detectors with both shallow entrance windows and adequate signal-to noise ratios to utilize the soft x-rays effectively. Low Gain Avalanche Detectors (LGADs) have the potential for improved signal-to-noise ratio due to the built-in amplification. However, the conventional LGAD structure is not conducive to a shallow entrance window. In this work, we propose a new LGAD device structure that can incorporate a shallow entrance window utilizing microwave annealing to activate the dopant in the entrance window. Process and device simulations are used to demonstrate the feasibility and performance of the proposed structure.

Through a high-precision soft x-ray magnetic circular dichroism (XMCD) study of the intermediate-valence compound $\mathrm{Sm}{\mathrm{Os}}_{4}{\mathrm{Sb}}_{12}$, we show our successful approach of revealing unprecedented details of Kondo screening below a characteristic temperature of ${T}_{0}\ensuremath{\sim}20$ K in the paramagnetic phase. The multiplet XMCD structure at the Sm ${M}_{5}$ edge sensitive to the $4f$ configuration enabled us to observe a clear difference between the temperature evolution above and below ${T}_{0}$ with one- and two-component behavior, respectively. Our findings are in strong contrast to the conventional Kondo crossover that coincides with the valence transition, but are qualitatively accounted for by theoretical XMCD predictions combined with the two-fluid phenomenology recently proposed. This work contributes to the large context of Kondo physics that is closely related to quantum criticality in heavy fermion systems.

The data of soft x-ray solar flare activity for the interval 2008 to 2019 which covers the ascending, maximum, descending & part of minimum period of solar cycle 24 has been used for investigating the behavior of North-South (N-S) and East-West (E-W) asymmetries. Our statistical analysis revealed that the N-S asymmetry is a real phenomenon and that the solar cycle 24 shows southern predominance which is similar to the past solar cycle 21, 22 and 23. Hence a long-term periodic behavior could be inferred. The E-W asymmetry for the considered is found to be slight western dominated but the associated probability values indicates a statistically insignificant result.

Isolated attosecond pulses (IAPs) produced through laser-driven high-harmonic generation (HHG) hold promise for unprecedented insight into physical, chemical, and biological processes via attosecond x-ray diffraction and spectroscopy with tabletop sources. Efficient scaling of HHG towards x-ray energies, however, has been hampered by ionization-induced plasma generation impeding the coherent buildup of high-harmonic radiation. Recently, it has been shown that these limitations can be overcome in the so-called “overdriven regime” where ionization loss and plasma dispersion strongly modify the driving laser pulse over small distances, albeit without demonstrating IAPs. Here, we report on experiments contrasting the generation of IAPs at 80 eV in argon with neon via attosecond streaking measurements. Comparing our experimental results to numerical simulations, we conclude that IAPs in argon are generated in the overdriven regime. We introduce a simple expression that fully describes the HHG dipole phase-mismatch contribution, specifically the effect of the blueshift of the driving laser. Furthermore, we present a method to numerically calculate the transient HHG phase mismatch, which allows us to demonstrate the accuracy of the introduced phase-mismatch expression. Finally, we perform simulations for different gases and wavelengths and show that including the full HHG dipole phase-mismatch contribution is important for understanding HHG with long-wavelength, few-cycle laser pulses in high-pressure gas targets, which are currently being employed for scaling isolated attosecond pulse generation beyond extreme ultraviolet (XUV) towards soft-x-ray photon energies.

We statistically study the relationship between the Lyman-alpha (\lya) and 1--8 \AA\ soft X-ray (SXR) emissions from 658 M- and X-class solar flares observed by the {\em Geostationary Operational Environmental Satellite} during 2006--2016. Based on the peak times of the two waveband emissions, we divide the flares into three types. Type I (III) has an earlier (a later) peak time in the \lya\ emission than that in the SXR emission, while type II has nearly a same peak time (within the time resolution of 10 s) between the \lya\ and SXR emissions. In these 658 flares, we find that there are 505 (76.8\%) type I flares, 10 (1.5\%) type II flares, and 143 (21.7\%) type III flares, and that the three types appear to have no dependence on the flare duration, flare location, or solar cycle. Besides the main peak, the \lya\ emission of the three type flares also shows sub-peaks which can appear in the impulsive or gradual phase of the flare. It is found that the main-peak (for type I) and sub-peak (for type III) emissions of \lya\ that appear in the impulsive phase follow the Neupert effect in general. This indicates that such \lya\ emissions are related to the nonthermal electron beam heating. While the main-peak (for type III) and sub-peak (for type I) emissions of \lya\ that appear in the gradual phase are supposed to be primarily contributed by the thermal plasma that cools down., Comment: 22 pages, 10 figures

We investigate the origin of the soft X-ray excess component in Seyfert galaxies observed when their luminosity exceeds 0.1% of the Eddington luminosity ($L_{\mathrm{Edd}}$). The evolution of a dense blob in radiatively inefficient accretion flow (RIAF) is simulated by applying a radiation magnetohydrodynamic code, CANS+R. When the accretion rate onto a $10^7M_{\odot}$ black hole exceeds 10% of the Eddington accretion rate ($\dot M_{\rm Edd}=L_{\rm Edd}/c^2$, where $c$ is the speed of light)}, the dense blob shrinks vertically because of radiative cooling and forms a Thomson thick, relatively cool ($\sim10^{7-8}$ K) region. The cool region coexists with the optically thin, hot ($T\sim10^{11}~\mathrm{K}$) RIAF near the black hole. The cool disk is responsible for the soft X-ray emission, while hard X-rays are emitted from the hot inner accretion flow. The soft X-ray emitting region coexists with the optically thin, hot ($T \sim 10^{11}~\mathrm{K}$), radiatively inefficient accretion flow (RIAF) near the black hole. Such a hybrid structure of hot and cool accretion flows is consistent with the observations of both hard and soft X-ray emissions from `changing-look' active galactic nuclei (CLAGN). Furthermore, we find that quasi-periodic oscillations (QPOs) are excited in the soft X-ray emitting region. These oscillations can be the origin of rapid X-ray time variabilities observed in CLAGN., 23 pages, 18 figures, Accepted for publication in ApJ

We evaluated laser-induced damage thresholds (LIDTs) on silica glasses by two kinds of ultra-short soft X-ray laser pulses (13.5 nm, 70 fs, and 13.9 nm, 7 ps). The comparison of our experimental results and the reported values observed by nanosecond soft X-ray pulse revealed a pulse width dependence of LIDTs on silica glasses in the soft X-ray region. The relationship between the pulse width and LIDTs provided valuable discussions of the laser-induced damage mechanism.

High-end precision optics are generally manufactured through traditional processes, which produce unique shapes and smooth surfaces, and the modern figure correction process. Particularly for soft x-ray regions, the demand for accurate free-form optics with complex and steep shapes has been increasing recently. Wolter mirrors and ring-focusing mirrors are representative of these types of optics, which are expected to be the next-generation devices for soft x-ray microscopy. To fabricate these mirrors with sufficient accuracy to achieve ideal optical performances, both traditional and modern processes must be optimized ad hoc. In this study, we apply the high-precision lens fabrication process to a monolithic Wolter mirror and a ring-focusing mirror. The surface measurement results of the mirrors suggest that it is possible to fabricate single-nanometer accurate soft x-ray mirrors with steep shapes in complex geometries.

The photocurrent (sample current) of insulating 0.7-μm thick polyethylene terephthalate (PET) films on conductive substrates (C, Au, Cu) was clearly measured through the substrates during soft X-ray irradiation on the PET films. X-ray absorption measurements of the PET/conductive-substrates using the total-electron-yield (TEY) method by measuring sample current easily provide the X-ray absorption spectra (XAS) of PET films, which are independent of the substrates. From additional X-ray absorption measurements using self-standing PET/Au and Au/PET-films, I-V measurements, and thickness-dependent sample current measurements, it can be confirmed that electrically conductive paths form in the insulating PET film in thickness direction along the soft X-ray beam trajectory. Such phenomena enable easy and simple TEY-XAS measurements of insulating μm-order-thick samples.

The active galactic nucleus (AGN) RE J1034+396 displays the most significant X-ray Quasi-Periodic Oscillation (QPO) detected so far. We perform a detailed spectral-timing analysis of our recent simultaneous XMM-Newton, NuSTAR and Swift observations. We present the energy dependence of the QPO's frequency, rms, coherence and phase lag, and model them together with the time-averaged spectra. Our study shows that four components are required to fit all the spectra. These components include an inner disc component (diskbb), two warm corona components (CompTT-1 and CompTT-2), and a hot corona component (nthComp). We find that diskbb, CompTT-2 (the hotter but less luminous component) and nthComp all contain the QPO signal, while CompTT-1 only exhibits stochastic variability. By fitting the lag spectrum, we find that the QPO in diskbb leads CompTT-2 by 679 s, and CompTT-2 leads nthComp by 180 s. By only varying the normalizations, these components can also produce good fits to the time-averaged and variability spectra obtained from previous observations when QPOs were present and absent. Our multi-wavelength study shows that the detectability of the QPO does not depend on the contemporaneous mass accretion rate. We do not detect a significant Iron K{\alpha} emission line, or any significant reflection hump. Finally, we show that the rms and lag spectra in the latest observation are very similar to the 67 Hz QPO observed in the micro-quasar GRS 1915+105. These new results support the physical analogy between these two sources. We speculate that the QPO in both sources is due to the expansion/contraction of the vertical structure in the inner disc., Comment: 22 pages, 17 figures, 6 tables, accepted by MNRAS

Silicon detectors are an essential measurement tool for Inertial Confinement Fusion and High-Energy-Density Physics Applications, where temporal response of the order of nanoseconds is essential. Soft X-rays (

Sc/Si multilayers are one of the promising material combinations commonly used in the spectral range of 35-50 nm. However, diffusion and silicidation at the interfaces of Sc/Si multilayers limit widespread applications of this material combination. To improve the properties of Sc/Si multilayers, the scheme of barrier layers is utilized. In this work, a series of Sc/Si multilayers with boron carbide and carbon barrier layers were designed and fabricated to compare the properties including interface quality and thermal stability. The effect on the multilayer structure and quality before and after annealing were investigated by using grazing-incidence X-ray reflection, X-ray diffraction, rocking-curve X-ray diffuse scattering, transmission electron microscopy, and selected area electron diffraction. The results indicate that severe interdiffusion and crystallization occur in the multilayer with a carbon barrier after annealing. However, a boron carbide barrier layer improves thermal stability up to 550 °C since the interfaces remain abrupt and clear after annealing. The multilayer quality is confirmed to be improved significantly.

The electronic structures of Gd-substituted Bi2−xGdxTe3 single crystals have been investigated by employing synchrotron-radiation spectroscopies, such as soft X-ray absorption spectroscopy (XAS), soft X-ray magnetic circular dichroism (XMCD), photoemission spectroscopy (PES), and scanning photoelectron microscopy (SPEM). SPEM measurements confirm that Gd ions are substituted homogeneously in Bi2−xGdxTe3 crystals. The measured Gd 3d XAS and XMCD spectra provide evidence that the substituted Gd ions are trivalent and magnetic. The hν-dependence of the valence-band (VB) PES spectra are described well by the hν-dependent contributions of the Te 5p and Bi 6p states. A good agreement is found between the measured VB PES spectra of Bi2−xGdxTe3 and the calculated partial densities of states, revealing that the Te 5p states will play an important role in determining the thermoelectric and topological properties of Bi2−xGdxTe3.

A hallmark of Parkinson's disease is the death of neuromelanin‐pigmented neurons, but the role of neuromelanin is unclear. The in situ characterization of neuromelanin remains dependent on detectable pigmentation, rather than direct quantification of neuromelanin. We show that direct, label‐free nanoscale visualization of neuromelanin and associated metal ions in human brain tissue can be achieved using synchrotron scanning transmission x‐ray microscopy (STXM), through a characteristic feature in the neuromelanin x‐ray absorption spectrum at 287.4 eV that is also present in iron‐free and iron‐laden synthetic neuromelanin. This is confirmed in consecutive brain sections by correlating STXM neuromelanin imaging with silver nitrate‐stained neuromelanin. Analysis suggests that the 1s–σ* (C−S) transition in benzothiazine groups accounts for this feature. This method illustrates the wider potential of STXM as a label‐free spectromicroscopy technique applicable to both organic and inorganic materials., Soft X‐ray spectromicroscopy enables neuromelanin visualization in human brain tissue. This removes dependence on optical evaluation of pigmentation or chemical staining, opening the door to investigating relationships between depigmentation, metal binding, and neurodegeneration in the most vulnerable neurons in Parkinson's disease. (Image of brain adapted, under license CCBY4.0, from Blausen.com staff, WikiJournal of Medicine 2014, 1, ISSN 2002–4436.)

Femtosecond X-ray absorption spectroscopy (XAS) is a powerful method to investigate the dynamical behavior of a system after photoabsorption in real time. So far, the application of this technique has remained limited to large-scale facilities, such as femtosliced synchrotrons and free-electron lasers (FEL). In this work, we demonstrate femtosecond time-resolved soft-X-ray absorption spectroscopy of liquid samples by combining a sub-micrometer-thin flat liquid jet with a high-harmonic tabletop source covering the entire water-window range (284–538 eV). Our work represents the first extension of tabletop XAS to the oxygen edge of a chemical sample in the liquid phase. In the time domain, our measurements resolve the gradual appearance of absorption features below the carbon K-edge of ethanol and methanol during strong-field ionization and trace the valence-shell ionization dynamics of the liquid alcohols with a temporal resolution of ∼30 fs. This technique opens unique opportunities to study molecular dynamics of chemical systems in the liquid phase with elemental, orbital, and site sensitivity. ISSN:1948-7185

Argon gas windows are shown to be effective for soft X-ray absorption spectroscopy in the low-energy region below 200 eV under atmospheric conditions., The soft X-ray region below 200 eV is important for investigating chemical and biological phenomena since it covers K-edges of Li and B and L-edges of Si, P, S and Cl. Helium gas is generally used as the soft X-ray transmission window for soft X-ray absorption spectroscopy (XAS) under atmospheric conditions. However, the helium gas window cannot be applied to XAS in the low-energy region since transmitted soft X-rays mostly consist of high-order X-rays due to the low transmission of first-order X-rays. In this study, the argon gas window is proposed as a new soft X-ray transmission window in the low-energy region. High-order X-rays are removed by the absorption of the Ar L-edge (240 eV), and first-order X-rays become the major contribution of transmitted soft X-rays in the low-energy region. Under atmospheric argon conditions, the double-excitation Rydberg series of helium gas (60 eV), Si L-edge XAS of an Si3N4 membrane (100 eV) and S L-edge XAS of di­methyl sulfoxide gas (170 eV) are successfully measured, indicating that the argon gas window is effective for soft X-ray transmission in the low-energy region from 60 eV to 240 eV.

Imaging of biological matter across resolution scales presents the challenge of preserving the direct and unambiguous correlation of subject features from the macroscopic to the microscopic level. We present here a correlative imaging platform developed specifically for imaging cells in 3D, under cryogenic conditions. Rapid cryo-preservation of biological specimens is the current gold standard in sample preparation for ultrastructural analysis in X-ray imaging. However, cryogenic fluorescence localisation methods are by and large diffraction-limited and fail to deliver matching resolution. We addressed this technological gap by developing an integrated, user-friendly, platform for 3D correlative imaging of cells in cryo-preserved states using super-resolution structured illumination microscopy (SIM) in conjunction with soft X-ray tomography (SXT). The power of this new approach is demonstrated by studying the process of reovirus release from intracellular vesicles during the early stages of infection and identifying novel virus-induced structures.

We demonstrate the feasibility of soft X-ray absorption spectroscopy in the water window using a table-top laser-based approach with organic molecules and inorganic salts in aqueous solution. A high-order harmonic source delivers femtosecond pulses of short wavelength radiation in the photon energy range from 220 to 450 eV. We report static soft X-ray absorption measurements in transmission on the solvated compounds O=C(NH

We have experimentally demonstrated circular polarization generation from linear polarized soft X-ray at synchrotron by adopting a thin magnetic film polarizer. Polarizer is composed of Co/Pt multilayer with a perpendicular magnetic anisotropy, which allows us to easily accommodate without needing any tilting angle into the measurement setup since the circular polarization is generated for the X-ray with normal incidence and transmission. Generated circular polarization is examined by observing magnetic domain features based on the X-ray magnetic circular dichroism, where ∼11% of circular component is estimated compared to the case of full circular polarization.

A new spatially coherent beamline has been designed and constructed at the Shanghai Synchrotron Radiation Facility. Here, the design of the beamline is introduced and the spatial coherence is analyzed throughout the whole process by wave optics. The simulation results show good spatial coherence at the endstation and have been proven by experiment results.

The six most stable isomers of C36 fullerene (8Cs-C36, 9C2v-C36, 11C2-C36, 12C2-C36, 14D2d-C36, 15D6h-C36) have been distinguished in theory by analysing their C1s X-ray photoelectron spectroscopy ...

In the present study, the optical constants of niobium carbide (NbC) in soft x-ray wavelength region of 6–15 nm have been determined using angle dependent x-ray reflectivity measurements. Experimentally measured optical constants (δ and β) are compared with tabulated values of Henke et al. The δ values are found 5–30% lower than the bulk value whereas deviation in beta values is around 5–38%. To the best of our knowledge, the present study gives the first reported experimental values of optical constants for niobium carbide in 6–15 nm wavelength range. The knowledge of experimentally measured optical constants of NbC will help in practical calculation of optical devices.

We briefly review the works concerned with the development and experimental use of the spectral instruments based on aperiodic reflection gratings whose spacing varies monotonically across the aperture according to a prescribed law (VLS gratings). The review considers the employment of VLS-grating instruments intended for the spectroscopy of laboratory and astrophysical plasmas, including the diagnostics of relativistic laser plasmas, for measuring X-ray laser linewidths, for recording the high-order harmonics of laser radiation, the radiation of fast electric discharges and other laboratory X-ray sources, as well as in reflectometry, X-ray fluorescence analysis and microscopy with the use of synchrotron radiation and laser-plasma radiation, and in emission spectroscopy combined with an electron microscope. Also discussed are achievements in the recently undertaken design and development of special-purpose VLS spectrometers intended for the investigation of the electronic structure of different materials and molecules by the spectroscopic technique of resonant inelastic X-ray scattering of synchrotron radiation. We describe flat-field grazing-incidence spectrometers with concave VLS gratings, which are compatible with modern CCD detectors, as well as plane VLS gratings, which are the key elements of scanning high- and ultrahigh-resolution spectrometers/monochromators with a constant deviation angle and stigmatic (imaging) spectrometers, which are also compatible with CCD detectors.

It is clear from the other articles in this issue that hard (tender) X-ray photoemission (HAXPES, HXPS) is a rapidly expanding aspect of photoemission, with existing or new facilities at most synch...

International audience; In the present study, surface and interface characterization of magnesium oxide (MgO) thin film is carried out by using non‐destructive soft X‐ray reflectivity and absorption technique. To get a further insight about the in‐depth and surface composition, secondary ion mass spectroscopy measurement is also carried out. The analysis of the reflectivity data indicates the presence of Mg‐Si‐O layer between the principal layer (MgO) and Si substrate interface. The secondary ion mass spectroscopy spectra corroborate well with the model assumed in the analysis of the reflectivity data. Combined soft X‐ray reflectivity‐total electron yield result confirms the presence of low‐density MgO on top of principal MgO layer. Total electron yield result confirms the rocksalt structure of the film and provides a glimpse of the electronic structure near the O‐K absorption edge.

Back in 1993, a first planar undulator was proposed, which produced circular (left and right) and vertical polarization, in addition to the standard linear horizontal polarization [1]. This flexibi...

Resonant inelastic X-ray scattering (RIXS) is a “photon in–photon out” technique through irradiating a sample with X-rays and detecting changes in energy and momentum between incident and scattered...

Cryo-soft X-ray tomography is an imaging technique that addresses the need for mesoscale imaging of cellular ultrastructure of relatively thick samples without the need for staining or chemical modification. It allows the imaging of cellular ultrastructure to a resolution of 25–40 nm and can be used in correlation with other imaging modalities, such as electron tomography and fluorescence microscopy, to further enhance the information content derived from biological samples. An overview of the technique, discussion of sample suitability and information about sample preparation, data collection and data analysis is presented here. Recent developments and future outlook are also discussed.

The question on the uniqueness of the solution of the problem of reconstructing a continuous soft X-ray emission spectrum by the iterative method [Nuclear Inst. and Methods in Physics Research A, 916 (2019) 313–321] from spectrograms obtained with a transmission diffraction grating is considered. It is shown that, despite the presence of a potentially infinite number of solutions of this problem, only one of them has the physical sense.