Photoelectron Spectral Yields Generated by Monochromatic Soft X Radiation

A magnetic spectrometer system has been developed to measure the energy spectra of photoelectrons generated by monochromatic soft x rays. Photo-electrons are detected with a channeltron electron multiplier and the count rates measured at each energy increment. Very-low-energy secondary electrons are detected by biasing the photoemitter to accelerate the electrons. Results are given for photoemission from standard aluminum foils excited by 1.74 and 1.49 keV x rays. Emission from aluminum dominates the higher-energy spectrum while the oxygen in the oxide layer dominates the softer spectrum. The total primary yields are (7.5 ± 2.0) × 10-3 and (2.0 ± 0.6) × 10-3 electrons/photon at 1.75 and 1.49 keV; the first value is about 25% less than the average of published data.