8 research outputs found
Near- and Extended-Edge X-Ray-Absorption Fine-Structure Spectroscopy Using Ultrafast Coherent High-Order Harmonic Supercontinua
Recent advances in high-order harmonic generation have made it possible to use a tabletop-scale setup to produce spatially and temporally coherent beams of light with bandwidth spanning 12 octaves, from the ultraviolet up to x-ray photon energies >1.6  keV. Here we demonstrate the use of this light for x-ray-absorption spectroscopy at the K- and L-absorption edges of solids at photon energies near 1 keV. We also report x-ray-absorption spectroscopy in the water window spectral region (284-543 eV) using a high flux high-order harmonic generation x-ray supercontinuum with 10^{9}  photons/s in 1% bandwidth, 3 orders of magnitude larger than has previously been possible using tabletop sources. Since this x-ray radiation emerges as a single attosecond-to-femtosecond pulse with peak brightness exceeding 10^{26}  photons/s/mrad^{2}/mm^{2}/1% bandwidth, these novel coherent x-ray sources are ideal for probing the fastest molecular and materials processes on femtosecond-to-attosecond time scales and picometer length scales.093002
A tabletop x-ray tomography instrument for nanometer-scale imaging: demonstration of the 1,000-element transition-edge sensor subarray
We report on the 1,000-element transition-edge sensor (TES) x-ray
spectrometer implementation of the TOMographic Circuit Analysis Tool (TOMCAT).
TOMCAT combines a high spatial resolution scanning electron microscope (SEM)
with a highly efficient and pixelated TES spectrometer to reconstruct
three-dimensional maps of nanoscale integrated circuits (ICs). A 240-pixel
prototype spectrometer was recently used to reconstruct ICs at the 130 nm
technology node, but to increase imaging speed to more practical levels, the
detector efficiency needs to be improved. For this reason, we are building a
spectrometer that will eventually contain 3,000 TES microcalorimeters read out
with microwave superconducting quantum interference device (SQUID)
multiplexing, and we currently have commissioned a 1,000 TES subarray. This
still represents a significant improvement from the 240-pixel system and allows
us to begin characterizing the full spectrometer performance. Of the 992
maximimum available readout channels, we have yielded 818 devices, representing
the largest number of TES x-ray microcalorimeters simultaneously read out to
date. These microcalorimeters have been optimized for pulse speed rather than
purely energy resolution, and we measure a FWHM energy resolution of 14 eV at
the 8.0 keV Cu K line.Comment: 5 pages, 4 figures, submitted to IEEE Transactions on Applied
Superconductivit
Atom Probe Tomography Using a Wavelength-Tunable Femtosecond-Pulsed Coherent Extreme Ultraviolet Light Source
Sub-picosecond, table-top x-ray absorption spectroscopy using superconducting microcalorimeters
We present time-resolved X-ray absorption measurements of vanadium dioxide using ionizations radiation generated by a femtosecond pulsed laser source in combination with superconducting microcalorimeters capable of measuring energies of individual radiation quanta
X-ray Spectrometer
An x-ray spectrometer includes: an x-ray plasma source that produces first x-rays; an x-ray optic in optical communication with the x-ray plasma source and that: receives the first x-rays from the x-ray plasma source; focuses the first x-rays to produce second x-rays; and communicates the second x-rays to a sample that produces product x-rays in response to receipt of the second x-rays and second light; and a microcalorimeter array detector in optical communication with the sample and that receives the product x-rays from the sample
Ultrafast Time-Resolved Hard X-Ray Emission Spectroscopy on a Tabletop
Experimental tools capable of monitoring both atomic and electronic structure on ultrafast (femtosecond to picosecond) time scales are needed for investigating photophysical processes fundamental to light harvesting, photocatalysis, energy and data storage, and optical display technologies. Time-resolved hard x-ray (>3  keV) spectroscopies have proven valuable for these measurements due to their elemental specificity and sensitivity to geometric and electronic structures. Here, we present the first tabletop apparatus capable of performing time-resolved x-ray emission spectroscopy. The time resolution of the apparatus is better than 6 ps. By combining a compact laser-driven plasma source with a highly efficient array of microcalorimeter x-ray detectors, we are able to observe photoinduced spin changes in an archetypal polypyridyl iron complex [Fe(2,2^{′}-bipyridine)_{3}]^{2+} and accurately measure the lifetime of the quintet spin state. Our results demonstrate that ultrafast hard x-ray emission spectroscopy is no longer confined to large facilities and now can be performed in conventional laboratories with 10 times better time resolution than at synchrotrons. Our results are enabled, in part, by a 100- to 1000-fold increase in x-ray collection efficiency compared to current techniques
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Near- and Extended-Edge X-Ray-Absorption Fine-Structure Spectroscopy Using Ultrafast Coherent High-Order Harmonic Supercontinua.
Recent advances in high-order harmonic generation have made it possible to use a tabletop-scale setup to produce spatially and temporally coherent beams of light with bandwidth spanning 12 octaves, from the ultraviolet up to x-ray photon energies >1.6  keV. Here we demonstrate the use of this light for x-ray-absorption spectroscopy at the K- and L-absorption edges of solids at photon energies near 1 keV. We also report x-ray-absorption spectroscopy in the water window spectral region (284-543 eV) using a high flux high-order harmonic generation x-ray supercontinuum with 10^{9}  photons/s in 1% bandwidth, 3 orders of magnitude larger than has previously been possible using tabletop sources. Since this x-ray radiation emerges as a single attosecond-to-femtosecond pulse with peak brightness exceeding 10^{26}  photons/s/mrad^{2}/mm^{2}/1% bandwidth, these novel coherent x-ray sources are ideal for probing the fastest molecular and materials processes on femtosecond-to-attosecond time scales and picometer length scales
Ultrafast Time-Resolved X‑ray Absorption Spectroscopy of Ferrioxalate Photolysis with a Laser Plasma X‑ray Source and Microcalorimeter Array
The detailed pathways of photoactivity
on ultrafast time scales are a topic of contemporary interest. Using
a tabletop apparatus based on a laser plasma X-ray source and an array
of cryogenic microcalorimeter X-ray detectors, we measured a transient
X-ray absorption spectrum during the ferrioxalate photoreduction reaction.
With these high-efficiency detectors, we observe the Fe K edge move
to lower energies and the amplitude of the extended X-ray absorption
fine structure reduce, consistent with a photoreduction mechanism
in which electron transfer precedes disassociation. These results
are compared to previously published transient X-ray absorption measurements
on the same reaction and found to be consistent with the results from
Ogi et al. and inconsistent with the results of Chen et al. (Ogi, Y.; et al. Struct.
Dyn. 2015, 2, 034901; Chen, J.; Zhang, H.; Tomov, I. V.; Ding, X.; Rentzepis, P. M. Chem.
Phys. Lett. 2007, 437, 50–55). We provide quantitative
limits on the Fe–O bond length change. Finally, we review potential
improvements to our measurement technique, highlighting the future
potential of tabletop X-ray science using microcalorimeter sensors