High resolution electron spectroscopy of atoms and molecules

Abstract

Recent progress in the high resolution gas phase electron spectroscopy using synchrotron radiation will be discussed with special emphasis to the Auger resonance Raman effect, which provides a unique method to overcome the effects of the lifetime broadening in resonance Auger spectra. Modern high resolution monochromators and electron spectrometers have made possible to obtain also in the VUV region total instrumental broadenings which are much smaller than the typical lifetime widths of the studied core levels. Examples of the use of the method to resolve experimentally the fine structure in resonance Auger spectra of rare gases and some simple molecules, are presented. The strength of the electron correlation effects can be studied now with much higher accuracy by comparing the observed intensity distributions with multiconfiguration Dirac-Fock predictions. Also the possible lineshape distortion of the resonance Auger spectra is discussed. The observed anomalous partial Auger decay rates in some molecules theifest the fact that the intensity distribution of Auger electrons depends on the exact nature of intermediate and final ionized states affected by spin-orbit and molecular interactions. Even strict propensity rules may appear if the intermediate and final state wavefunctions have perpendicular space orientations.