XFEL resonant photo-pumping of dense plasmas and dynamic evolution of autoionizing core hole states. (March 2016)

• Record Type: Journal Article
• Authors: Rosmej, F B; Moinard, A; Renner, O; Galtier, E; Lee, J J; Nagler, B; Heimann, P A; Schlotter, W; Turner, J J; Lee, R W; Makita, M; Riley, D; Seely, J
• Is Part Of: Journal of physics. Volume 688(2016)
• Publication Date: 2016-03
• Subjects: Physics -- Congresses; 530.5
• DOI: 10.1088/1742-6596/688/1/012093
• Languages: English
• ISSNs: 1742-6588

Abstract

Abstract: Similarly to the case of LIF (Laser-Induced Fluorescence), an equally revolutionary impact to science is expected from resonant X-ray photo-pumping. It will particularly contribute to a progress in high energy density science: pumped core hole states create X-ray transitions that can escape dense matter on a 10 fs-time scale without essential photoabsorption, thus providing a unique possibility to study matter under extreme conditions. In the first proof of principle experiment at the X-ray Free Electron Laser LCLS at SCLAC [Seely, J., Rosmej, F.B., Shepherd, R., Riley, D., Lee, R.W. Proposal to Perform the 1 st High Energy Density Plasma Spectroscopic Pump/Probe Experiment", approved LCLS proposal L332 (2010)] we have successfully pumped inner-shell X-ray transitions in dense plasmas. The plasma was generated with a YAG laser irradiating solid Al and Mg targets attached to a rotating cylinder. In parallel to the optical laser beam, the XFEL was focused into the plasma plume at different delay times and pump energies. Pumped X-ray transitions have been observed with a spherically bent crystal spectrometer coupled to a Princeton CCD. By using this experimental configuration, we have simultaneously achieved extremely high spectral (λ/δλ ≈ 5000) and spatial resolution (δx≈70 μm) while maintaining high luminosity and a large spectral range covered (6.90 - 8.35 Å). By precisely measuring the variations in spectra emitted from plasma under action of XFEL radiation, we have successfully demonstrated transient X- ray pumping in a dense plasma.