Interference effects in Auger resonant Raman spectra of CO via selective vibrational excitations across the O1s→2πresonance

Abstract

The Auger resonant Raman spectra of CO, arising from the transitions to the $X$ and $A$ final electronic states of $\mathrm{C}{\mathrm{O}}^{+}$, have been recorded at photon energies corresponding to the vibrational excitations ${v}^{\ensuremath{'}}=3,5$, and 8 in the O $1s\ensuremath{\rightarrow}2\ensuremath{\pi}$ resonance. The spectra are simulated within the model that takes into account both the lifetime-vibrational interference (LVI) and interference with the nonresonant photoemission. The spectroscopic parameters, ${\ensuremath{\omega}}_{e}$, ${\ensuremath{\omega}}_{e}{x}_{e}$, $\ensuremath{\Gamma}$ and ${r}_{e}$, of the O $1{s}^{\ensuremath{-}1}2\ensuremath{\pi}$ core-excited state, necessary for the simulation, have been derived by fitting the Franck-Condon simulation to the total ion yield spectrum, assuming a Morse potential for the O $1{s}^{\ensuremath{-}1}2\ensuremath{\pi}$ state. Not only the LVI but also the interference with the nonresonant photoemission turn out to be significant.