X‐Ray Absorption Spectroscopy on Free Molecules

Abstract

Abstract The most recent spectroscopic method that can be applied to chemical problems is X‐ray absorption spectroscopy, in which the excitation of individual core electrons of an atom is studied. The analysis of the spectra with the aid of simple theoretical models yields information both about the core orbitals of the atom and about the unoccupied molecular orbitals, from which various molecular properties can be deduced. These not only include charge distribution, electronic configuration, geometry, and spatial and energy characteristics of orbitals of the molecule under investigation; one can also obtain parameters of radicals (such as stability, bond length, ionization potential, and electronic excitation energy) that differ from the molecule under investigation in that the nuclear charge of one atom is one unit higher.