Carbon1score-hole lifetime inCO2

Abstract

The carbon $1s$ photoelectron spectrum has been measured for ${\mathrm{CO}}_2$ at photon energies of 308, 320, and 330 eV with an instrumental resolution about half the natural linewidth. These spectra have been analyzed to obtain vibrational spacings, vibrational intensities, and the lifetime, τ, of the carbon $1s$ core-hole state. Theoretical calculation of the lifetime width, ħ/τ, using a one-center model, which assumes that only the valence electrons localized on the atom with the core hole can participate in Auger deexcitation of the core hole, predicts a value of 66 meV, considerably smaller than that predicted for ${\mathrm{CH}}_4$ (96 meV). Experimental measurements indicate, however, that the ${\mathrm{CO}}_2$ carbon $1s$ width is, in fact, much larger than expected—$99\pm 2\mathrm{meV}$—and is approximately the same as that found experimentally for ${\mathrm{CH}}_4$ (95±2 meV). This result indicates that valence electrons on the oxygen atoms may play a role in the Auger decay the carbon $1s$ core hole in ${\mathrm{CO}}_2,$ and, hence, that a multicenter model may be necessary to describe the Auger process.