Electronic-state interference in the C 1 s excitation and decay of methyl chloride studied by angularly resolved Auger spectroscopy
Résumé
Resonant Auger (RA) decay spectra of carbon 1s excited CH3Cl molecules are recorded with angular resolution
using linearly polarized synchrotron radiation. The selected photon energies corresponding to the C 1s → 8a1
core to lowest unoccupied molecular orbital and C 1s → 4sa1, 4pe, and 4pa1 core to Rydberg excitations of
methyl chloride are used and electrons in the binding energy range of 11–37 eV are detected. The vibrationally
unresolved RA electron angular distributions, recorded for participator Auger transitions populating the X, A,
B, and C states of the CH3Cl+ ion, exhibit strong variations across the selected electronic resonances. These
observations are interpreted with the help of ab initio electronic structure and dynamics calculations, which
account for electronic-state interference between the direct and different resonant ionization pathways. For
spectator transitions, the theory predicts almost isotropic angular distributions with moderate changes of β
parameters around zero, which is in agreement with the experimental observations.