Single-photon multiple ionization of argon in the K-edge region.

Abstract

The individual charge state and total ion yields resulting from the photoionization of argon gas have been measured as a function of photon energy through the [ital K] edge using synchrotron radiation and time-of-flight spectroscopy. We have formulated a model for the mean ion charge [ital [bar q]]([ital h][nu]) observed at nominal photon energy [ital h][nu], and have determined the mean ion charge [ital [bar q]] resulting from the decay of the atom following [1[ital s]]4[ital p], [1[ital s]]5[ital p], and [1[ital s]][var epsilon][ital p] photoabsorption. We have also characterized the energy-dependent photoelectron recapture probability due to postcollision interaction. In contrast with the recent analysis by Doppelfeld [ital et] [ital al]. [J. Phys. B 26, 445 (1993)], we find that the gradual increase in [ital [bar q]]([ital h][nu]) that begins approximately 20 eV below the argon [ital K] edge can be attributed to lifetime energy broadening of the [ital K]-hole state and the finite energy width of the x-ray source.