Vibronic coupling and core-hole localization in<i>K</i>-shell excitations of ethylene

Abstract

A new high-resolution measurement of the C 1s near-edge photoabsorption spectrum of the ethylene molecule is reported. An analysis of the vibrational structure in the C 1s-${\mathrm{\ensuremath{\pi}}}^{\mathrm{*}}$ band indicates strong excitation of non-totally-symmetry modes and the importance of vibronic coupling. The latter phenomenon provides a mechanism for core-hole localization in the final state.