DETERMINATION OF MOLECULAR-CONFORMATION FROM LARGE-AMPLITUDE VIBRATIONS IN ELECTRONIC-SPECTRA OF ORGANIC-MOLECULES IN A SUPERSONIC JET

Molecules having low wavenumber, large amplitude vibrations are easily distorted in the direction of the corresponding normal mode. Therefore the conformation may be changed appreciably when a molecule is excited from its ground state to another electronic state and there is a tendency for low wavenumber vibrations to have large Franck-Condon factors in electronic transitions. The resulting vibrational progressions can be used to access many levels of what may be inversion, ring-puckering, or torsional vibrations. Fitting these levels to a model potential allows the conformation of the molecule to be obtained.