INTERACTION BETWEEN THEORY AND EXPERIMENT IN MOLECULAR CORE ELECTRON SPECTROSCOPIES

The interaction between theory and experiment in the field of molecular core electron spectroscopies is reviewed. Those aspects that distinguish the theoretical descriptions of core and valence electron spectra are analyzed in particular. Differences in the theoretical approaches to atomic and molecular spectra in terms of scattering and many-body theories are commented on. The molecular core electron spectroscopies are analyzed from a common point of view with respect to molecular orbital theory, many-body theory, and the role of localization and local selection rules. A brief analysis is presented for the particularities that enter the calculations of core hole spectra. Solutions are described to computational problems posed by the quasi-bound, highly excited nature of core hole states and by the large electronic relaxation following their creation. Two areas where the interaction between theory and experiment is particularly fruitful are briefly reviewed, namely, the theory of vibronic excitations in core electron spectra and the theory of the core photoelectron chemical shift.