Electronic Structure Investigation of Highly Compressed Aluminum withKEdge Absorption Spectroscopy

Abstract

The electronic structure evolution of highly compressed aluminum has been investigated using time resolved K edge x-ray absorption spectroscopy. A long laser pulse (500 ps, I(L)≈8×10(13) W/cm(2)) was used to create a uniform shock. A second ps pulse (I(L)≈10(17) W/cm(2)) generated an ultrashort broadband x-ray source near the Al K edge. The main target was designed to probe aluminum at reshocked conditions up to now unexplored (3 times the solid density and temperatures around 8 eV). The hydrodynamical conditions were obtained using rear side visible diagnostics. Data were compared to ab initio and dense plasma calculations, indicating potential improvements in either description. This comparison shows that x-ray-absorption near-edge structure measurements provide a unique capability to probe matter at these extreme conditions and severally constrains theoretical approaches currently used.

X-ray absorption spectroscopy of iron at multimegabar pressures in laser shock experiments

“…In addition, signatures of molten iron in the XANES spectra were predicted using first principles simulations [16,17]. Following recent progresses using (XANES) spectroscopy in dynamical experiments [18][19][20], we used XANES spectroscopy to determine whether similar signatures could exist along the principal Hugoniot. Compared to X-ray diffuse scattering [4], the X-ray absorption technique offers the advantage of a higher cross section and therefore requires a lower photon number and thinner samples that are easier to compress homogeneously.…”

Observation of Betatron X-Ray Radiation in a Self-Modulated Laser Wakefield Accelerator Driven with Picosecond Laser Pulses

“…emission successfully used for single-shot x-ray absorption near edge structure (XANES) [32], a technique widely used to diagnose shock-compressed and warm dense matter [33][34][35]. Using betatron radiation to this end will greatly benefit from efficient x-ray focusing optics [36], x-ray spectrometer designs [37], and increased yield for kilojoule laser systems [9].…”

Density functional theory calculations of continuum lowering in strongly coupled plasmas

“…The use of excited potentials in DFT calculations to study the electronic structure, often investigated experimentally by photoemission spectroscopy, is an established technique [22][23][24][25] , and has been recently adapted to the frozen-core PAW formalism to study the properties of dense plasmas 26 . This technique has since been successfully applied to interpret XANES measurements on dense Al plasmas with a 1s core hole 27 , and to the study of X-ray emission spectroscopy and electronic structure of L-shell-excited Al on the VUV FEL FLASH 28 .…”