MULTI-PHOTON IONIZATION SPECTRA OF BENZENE, FLUOROBENZENE, AND CHLOROBENZENE RESONANT WITH S0-S1 TRANSITIONS BY USE OF NOZZLE BEAM METHOD

Multiphoton ionization technique combined with nozzle beam method was applied to the observation of two-photon absorption spectra of benzene, fluorobenzene, and chlorobenzene in S0-S1 valence shell excitations. Strong two-photon activity of v14 (b2u or b2) vibration throughout these molecules was established. Details of the multiphoton ionization spectrum of chlorobenzene which was observed for the first time will be given. It was concluded that the two-photon resonant four-photon ionization spectra obtained in the present work reflect correct two-photon absorption cross sections. The vibrational temperature of a lower frequency vibration was found to decrease preferentially in an expanded low temperature nozzle beam. © 1980 American Institute of Physics.