RESONANCES AND THE EFFECTS OF INTERCHANNEL COUPLING IN THE PHOTOIONIZATION OF CS2
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The photoionization cross sections of CS2 leading to the X 2g, A 2u, B 2u+, and C 2 g+ states of CS2+ have been computed including the effects of interchannel coupling in the multi-channel frozen core Hartree-Fock approximation. The results were obtained using the iterative Schwinger variational method using a partial wave expansion up to l=120. The photoionization cross sections are obtained in the mixed dipole representation which ensures that the Thomas-Reiche-Kuhn sum rule is satisfied. We have found shape resonances in the kg and ku continuum channels. In particular, the kg resonance is seen to affect dramatically both total cross sections and photoelectron asymmetry parameters in all other channels when interchannel coupling is included. The form of the resonant wave function indicates that this resonance is caused by low lying virtual d orbitals on the sulfur atoms. Using a Schwinger-type iterative method we have found the position of the corresponding poles of the single channel T matrix in the complex plane. We have determined that the position of the pole is relatively insensitive to the interatomic bond lengths. This is indicative of the atomic nature of the resonant state. We have also determined cross sections and asymmetry parameters in the region of autoionization in the channel leading to the X 2g state of CS2+. 1992 American Institute of Physics.
