TIME-DEPENDENT THEORY OF THE AUGER RESONANT RAMAN EFFECT FOR DIATOMIC-MOLECULES - CONCEPTS AND MODEL-CALCULATIONS FOR N-2 AND CO

We develop an explicitly time-dependent theory for one-step resonant e xcitation-deexcitation processes of core electron states in diatomic m olecules. Emphasis is placed on a conceptual picture demonstrating how the effective time of the formation of the spectra-which is influence d by the bandwidth of the exciting radiation, by the excitation of the molecule being resonant or off resonant (detuned), and by the actual core hole lifetime-changes the appearance of the deexcitation electron spectra. Explicit time-dependent model calculations for three final S tates each of 1s-hole excited N-2 (including one spectator decay) and C 1s-hole excited CO allow demonstration of the various consequences f or the spectral shapes which derive from these influences. In particul ar, off-resonance excitation is;shown to shorten the effective time of the spectrum formation below the lifetime of the core-excited state l eading to the recently observed collapse of the vibrational structure in the spectrum. Our calculated spectra also demonstrate the influence s of the relative positions and shapes of the potential curves involve d. On resonance, the nodal structure of the vibrational wave functions of the core-excited state is reflected in the shapes of the spectator decay spectra of N-2 with a soft final state interatomic potential. [ S1050-2947(98)05308-6].