ULTRAVIOLET PHOTOELECTRON STUDIES OF THE MOLECULES SE5, SE6, SE7 AND SE8 WITH RELEVANCE TO THEIR GEOMETRICAL STRUCTURE

The vacuum-UV-photoelectron spectra (hv = 10.0 eV) of Se2, Se5, Se6, Se7, and Se8 were measured. The isolated particles were examined in a supersonic molecular beam employing the photoelectron-photocation-coincidence technique. The structures of the photoelectron spectra of selenium molecules with even and odd numbers of atoms differ in a characteristic manner. Whereas the spectra of Se6 and Se8 show one single broad band, three separated bands with different intensities are observed for Se5 and two for Se7. An attempt to connect these experimental observations with the geometrical structure of the molecules shows that the photoelectron spectra are consistent with the C1h-symmetry of the Se5 and Se7 rings proposed in the literature.