Knowledge Bank

The multiphoton ionization spectrum of benzene was taken in a seeded supersonic beam in the region of the two-photon resonances with the $A1B2u$ state. Ionization data was obtained beyond the fluorescence limit at $41,300cm-1$. Due to the almost complete rotational and vibrational cooling in the beam expansion the linewidths of the vibronic levels were able to be monitored directly from the spectra as a function of energy above the electronic origin $T00$ without interference from hot rotational contours. This two-photon data has important implications to the understanding of the channel 3 non-radiative process in benzene. In addition to following the variations in the vibronic level line-widths, new bands were seen $6-8cm-1$ from the dominant $140110n$ progression. In addition, at the high resolution of this experiment splitting was found in the previously $seen1$ unidentified $Y01$ bands in benzene-$d6$.