Photoelectron Energy Spectra Generated by Low-Energy X Rays from Intense Plasmas

A magnetic spectrometer has been used to measure the energy spectrum of primary photoelectrons generated by pulsed low-energy x rays from an exploding aluminum-wire source. The photoelectrons were detected by a set of eight Faraday cups covering the range of 0.2 to 4.0 keV and the time resolution of the system was better than 4 nsec. Surfaces studied were Au, Ag, Al, Al2O3, C, and Kapton. The measured photoelectron energy spectra and derived yields are consistent with the energy-dependent absorption cross sections of the various materials; most of the electrons from aluminum originated from the Auger effect. Results also confirmed that the angular distribution followed a cos ¿ distribution with respect to the surface normal.