Conventional Fourier-transform infrared (FTIR) microspectroscopic systems are limited by an inevitable trade-off between spatial resolution, acquisition time, signal-to-noise ratio (SNR) and sample coverage. We present an FTIR imaging approach that substantially extends current capabilities by combining multiple synchrotron beams with wide-field detection. This advance allows truly diffraction-limited high-resolution imaging over the entire mid-infrared spectrum with high chemical sensitivity and fast acquisition speed while maintaining high-quality SNR.

For the first time, the evolution ofluminescence from rare gases was studied as a function of number density. Synchrotron radiation served as a light source for selective and pulsed excitation of the samples. The excitation spectra confirm previous results on perturbed Rydberg states and exciton appearance in dense media. In time-resolved emission spectra the peak energies and widths of the luminescence bands were followed. The energy separation between the fast and slow components is found to be density independent. A model proposed by Cheshnovsky et al. [Chern. Phys. Lett. 15, 475 (1972)] accounts for the change in peak width with temperature. Both lifetimes decrease with increasing density. The data extrapolate to 3.3 ± 0.1 ns (Ar); 3.4 ± 0.1 ns, 270 ± 5 ns (Kr); 4.5 ± 0.1 ns, 100 ± 5 ns (Xe) for the low density limit. For the solid at the triple point, we obtain 1.3 ± 0.1 ns, 82 ± 5 ns (Kr) and1.1 ± 0.1 ns, 18.5 ± 0.5 ns (Xe). Theories on density dependence oflifetimes give only a qualitative description of the experimental results.

Over the past decade, the advances in grating-based soft X-ray spectrometers have revolutionized the soft X-ray spectroscopies in materials research. However, these novel spectrometers are mostly dedicated designs, which cannot be easily adopted for applications with diverging demands. Here we present a versatile spectrometer design concept based on the Hettrick-Underwood optical scheme that uses modular mechanical components. The spectrometer's optics chamber can be used with gratings operated in either inside or outside orders, and the detector assembly can be reconfigured accordingly. The spectrometer can be designed to have high spectral resolution, exceeding 10 000 resolving power when using small source (∼1μm) and detector pixels (∼5μm) with high line density gratings (∼3000 lines/mm), or high throughput at moderate resolution. We report two such spectrometers with slightly different design goals and optical parameters in this paper. We show that the spectrometer with high throughput and large energy window is particularly useful for studying the sustainable energy materials. We demonstrate that the extensive resonant inelastic X-ray scattering (RIXS) map of battery cathode material LiNiCoMnO can be produced in few hours using such a spectrometer. Unlike analyzing only a handful of RIXS spectra taken at selected excitation photon energies across the elemental absorption edges to determine various spectral features like the localized dd excitations and non-resonant fluorescence emissions, these features can be easily identified in the RIXS maps. Studying such RIXS maps could reveal novel transition metal redox in battery compounds that are sometimes hard to be unambiguously identified in X-ray absorption and emission spectra. We propose that this modular spectrometer design can serve as the platform for further customization to meet specific scientific demands.

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A new method for beamline simulation combining ray-tracing and wavefront propagation is described. The 'Hybrid Method' computes diffraction effects when the beam is clipped by an aperture or mirror length and can also simulate the effect of figure errors in the optical elements when diffraction is present. The effect of different spatial frequencies of figure errors on the image is compared with SHADOW results pointing to the limitations of the latter. The code has been benchmarked against the multi-electron version of SRW in one dimension to show its validity in the case of fully, partially and non-coherent beams. The results demonstrate that the code is considerably faster than the multi-electron version of SRW and is therefore a useful tool for beamline design and optimization.