Absolute photoabsorption measurements of Mg, Al, and Si in the soft-x-ray region below theL2,3edges

Abstract

Absolute measurements of the photoabsorption coefFicient of Mg, Al, and Si from 25 eV up to the L3 absorption edge are presented. Transmission measurements were performed on free-standing thin films using a laser-produced plasma source. The surface oxide is corrected for by taking the ratio of the absorption for different film thicknesses. The values so obtained are, in general, lower than have been reported in the literature. Structure below the edge is observed for Al and Si. Despite the fact that the absorption below the L3 edge is due to the valence or conduction electrons, the magnitude of the absorption coefBcient for the solid is much higher than is predicted by a simple Drude model and is close to that expected from calculations for the free atom.

Warm Dense Matter Demonstrating Non-Drude Conductivity from Observations of Nonlinear Plasmon Damping

“…By comparing with new accurate angularly-and spectrallyresolved scattering measurements from LCLS, we found, for the first time, a very good agreement between the complete X-ray Thomson scattering spectrum including all contributions that validate our full scale simulations with HSE. Moreover, our experimental data and simulations allow the experimental observation and theoretical interpretation of nonlinearly damped plasmons where the plasmon width is smaller than predicted by the RPA indicating non-Drude conductivities [49]. Previous investigations have studied non-Drude behavior due to localization of bound atomic states in expanding low-density plasmas [28,50].…”

Observation of multiply ionized plasmas with dominant bound electron contribution to the index of refraction

“…4. From all elements with atomic number (Z) less than 54, Al is the only one that has a negative f 0 1 [16,17] due to the close proximity of the 84.4 eV photon energy to the Al L-shell absorption edge. Some elements with ZX54, including I, Xe, Cs, Ba, Fr, Ra, Ac, also have a negative scattering factor at this wavelength.…”

Microscopie interférentielle X-UV de plasmas créés par laser

“…Une situation extrême est celle d'un plasma suffisamment refroidi pour redevenir une vapeur d'aluminium (absence d'électrons libres). L'indice de réfraction de cette vapeur peutêtre calculéà partir des coefficients complexes de diffusion atomique [11]. Pour une densité particulaire de 10 20 atomes d'aluminium par cm [10].…”