The electron spectrum of the M 2 and M 3 levels in bromine and krypton have been studied by high resolution ESCA. The M 1 M 2,3 M 2,3 super Coster-Kronig transitions become energetically forbidden for Zless than sim-36 (Kr) and recent calculations therefore predict a decrease in the M 2 and M 3 natural linewidths around krypton in the periodic system. The experiment shows that the 3p 3/2 linewidth is smaller in Kr than in Br. It is, however, also found that this decrease in linewidth is followed by configuration interaction (CI) between 3p 2 P and 3d 2 nl*2 P states. Several descrete CI resonances are observed in the Kr 3p spectrum. Such resonances are also studied in the N shell for the elements from Te (Z = 52) to Ba (Z = 56). For these elements the effect is found to be much larger due to the strong collective character of 4d-nf* excitations.

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Experimental and theoretical studies of the doubly charged NO2+ 2 ionThe N1s (NO,) ESCA spectrum of para nitro aniline (PNA) is analyzed theoretically and experimentally. New monochromatized high-resolution spectra in the vapor (gas) and condensed phases are presented. In the condensed phase spectrum two distinct peaks are discerned. whereas the gas phase spectrum shows a drastically different feature in which the two peaks are reduced to an asymmetric band. The gas phase spectrum has been interpreted based on large-scale MCSCF wave functions calculated using a complete configuration expansion in the 1T valence orbital space. Emphasis is placed on the identification of features due to "shake" effects. Multiple excitations in the charge transfer excited states, as well as configuration neardegeneracy effects in the NO, group, are found to be crucial for this identification. Our results are different from an earlier many-body, Green's function, treatment ofPNA. We find that the charge transfer shake states lie higher in energy (shakeup) and not lower (negative shakeup).

A high resolution ESCA spectrum of C2H2 was recorded using monochromatized AlKα excitation and was analyzed by means of configuration interaction and multiple configuration SCF wave functions. The role of different schemes for electron-configurational selection in the initial and final states on transition moments and energies was investigated. The spectrum shows a prominent satellite structure in the inner valence region, which is analyzed and discussed in terms of electron correlation, dissociative photoionization, interference, and vibronic coupling effects.

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