Experimental Evidence for the Breakdown of Uniform-Electron-Gas Models in Warm Dense Aluminium
/ Authors
D. Bespalov, U. Zastrau, Z. Moldabekov, T. Gawne, T. Dornheim, Moyassar M. Meshhal, A. Amouretti, Michał Andrzejewski, K. Appel, C. Baehtz
and 52 more authors
E. Brambrink, K. Buakor, Carolina M. Camarda, D. Chin, Gilbert W. Collins, C. Crépisson, A. Descamps, Jon Eggert, L. Fletcher, A. Forte, G. Gregori, M. Harmand, O. Humphries, Hauke Hoeppner, J. Kuhlke, William Lynn, Julian Luetgert, M. Masruri, Emma M. McBride, R. McWilliams, A. Mora, Jean-Paul Naedler, Paul Neumayer, Charlotte Palmer, A. Pelka, L. Pennacchioni, D. Polsin, C. Prestwood, Natalia Pukhareva, C. Qu, Divyanshu Ranjan, R. Redmer, M. Roeper, C. Sahle, Samuel Schumacher, Jan-Patrick Schwinkendorf, Melanie J. Sieber, Madison Singleton, Ethan Smith, C. Sternemann, T. Stevens, Michael Stevenson, C. Strohm, M. Tang, M. Toncian, T. Toncian, T. Tschentscher, S. Vinko, J. Wark, Max Wilke, D. Kraus, T. Preston
/ Abstract
The robust diagnosis of thermodynamic conditions in warm dense matter experiments remains a central challenge. We report angle-resolved femtosecond x-ray Thomson scattering measurements of shock-compressed aluminum at approximately 50 GPa over a wide range of scattering wavevectors at the European XFEL. The measured plasmon dispersion and line shape demonstrate that the standard analysis of x-ray Thomson scattering spectra based on uniform electron gas models systematically overestimates the plasmon resonance energy by up to 8 eV. In contrast, an analysis based on ab initio calculations reproduces both the dispersion and spectral shape within experimental uncertainty. Our results show that shock-induced disorder plays a critical role in the interpretation of x-ray Thomson scattering from compressed solids and provide direct evidence that ab initio approaches are required for reliable inference of thermodynamic conditions in warm dense aluminum.