Single and Double Core-Hole Ionization Energies in Molecules

Abstract

The recently demonstrated ability to measure double-hole core-ionization energies in first-row elements has led to a renewed interest in the use of such energies to investigate the effects of initial-state charge distribution and final-state charge rearrangement on the energies of chemical processes that involve addition of charge to a molecule. With theoretical calculations for the molecules CH(4-n)X(n), X = F, Cl, and for C(CH(3))(4) as a basis, the relationships between one-hole and two-hole ionization energies, on one hand, and initial-state and final-state effects, on the other, are reviewed. It is shown that higher-order corrections to the traditionally used relationships are quantitatively significant but do not lead to qualitatively different conclusions. The role of the Wagner plot as a way to display the relationships among the various quantities of interest is discussed, and a generalized Wagner plot for displaying two-site double-hole ionization energies is presented. Some possible applications of measurements of double-hole ionization energies to the investigation of molecular conformation and molecular fragmentation are discussed.

Single photon simultaneous K-shell ionization and K-shell excitation. I. Theoretical model applied to the interpretation of experimental results on H2O

“…[4][5][6][7][8] The chemical shift sensitivity to the location of core holes was confirmed recently with the observation of K −1 K −1 signals. [9][10][11][12][13] On the theoretical side, K −2 molecular states were investigated recently, [14][15][16][17][18][19] mostly by means of the complete active space self-consistent field (CASSCF) method or the density functional theory (DFT). Auger decay rates of DCH states were also computed.…”

Formation and decay of core-orbital vacancies in the water molecule

“…[13][14][15][16] and references therein) or shake-off states and their energies and decay processes are hitherto unknown. At even higher energies it becomes possible to create a double vacancy in the core, that is, in the present context, a hollow molecule with no electrons left in the 1s orbital [17][18][19][20][21][22][23][24][25][26][27][28]. States of this sort are so far unknown in water, but certainly of interest and possibly significant.…”

Homonuclear site-specific photochemistry by an ion–electron multi-coincidence spectroscopy technique

“…Refs. [27][28][29][30]) because of the coulomb repulsion. Secondly, the electrons taking part in the Auger effect come from orbitals with greatest density at the core-hole site; generally the bond weakening upon their loss will also be located in the same vicinity.…”