Multiphoton ionization of rare gases using multichannel-quantum-defect theory

Abstract

We apply multichannel-quantum-defect theory (MQDT) to multiphoton ionization of rare gases in lowest-order perturbation theory. We determine MQDT parameters of J=1,3 odd-parity states, J=0,2 even-parity states in xenon and krypton by fitting experimental energy levels and constructing Lu-Fano plots. We present calculations of two- and three-photon ionization of xenon and krypton in the autoionization region between the two thresholds. We compare autoionization spectra and also photoelectron angular distributions to experimental data [S. T. Pratt, P. M. Dehmer, and J. L. Dehmer, Phys. Rev. A 35, 3793 (1986); J. L. Dehmer, S. T. Pratt, and P. M. Dehmer, ibid. $fat 36---, 4494 (1987)]. Agreement between theory and experiment is reasonable, especially for krypton.