DUSCHINSKY EFFECT IN SUM-FREQUENCY GENERATION FROM ADSORBED MOLECULES

It is the purpose of this work to give a theoretical description of th e role played by the Duschinsky rotation in sum frequency generation e xperiments performed on adsorbed molecules. In addition to the mode mi xing resulting from the Duschinsky rotation, frequency shifts as well as nuclear equilibrium position shifts, occuring under electronic exci tation, are incorporated in the present model. The sum frequency gener ation spectra are calculated in order to compare the effects of the eq uilibrium position shifts and the quadratic mode mixing.