COLLAPSE OF VIBRATIONAL STRUCTURE IN THE AUGER RESONANT RAMAN-SPECTRUM OF CO BY FREQUENCY DETUNING

Observations made in the C1s-->pi Auger resonant Raman spectra of car bon monoxide demonstrate that the vibrational structure in such spectr a is strongly frequency dependent. In the limit of narrow bandpass pho ton excitation, the vibrational excitations of the 5 sigma participato r transition collapse to one single line within a sub-eV detuning rang e. The effect is explained in terms of a generalized duration One for the resonance process, in which the lifetime;of the core excited state and the inverse of the detuning frequency play equal roles.