VIBRONIC SPECTRA OF THE BENZENE CRYSTAL AT 4.2-K USING 2-PHOTON FLUORESCENCE EXCITATION

The two-photon excitation spectra of benzene crystals have been determined in the range 530 to 400 nm. The spectra can be related to approximately C 2h symmetry benzene molecules. The E-type bands are all split by the crystal field as is already known for the one-photon absorption, the Raman, and the infrared spectra. The study has allowed the determination of the two-photon tensors for the eight ungerade vibrational fundamentals V11, V 14-V19 in the crystal axis system. The oriented gas transformation provides in this case an approximate diagonalization of the crystal axis based tensors. The two-photon excitation spectra are rich in two particle effects. © 1979 American Institute of Physics.