SUPERSONIC FREE JET AND AB-INITIO STUDIES OF ELECTRONIC-VIBRATIONAL STRUCTURES OF FLUORENE

Laser-induced fluorescence (LIF) excitation spectra were measured for fluorene (FR) cooled in pulsed supersonic expansions of He in the rang e 283.7-296.7 nm. Ab initio studies of FR have also been carried out f or determining the electronic and vibrational structures by using the standard 3-21G basis sets. In the LIF excitation spectra of FR highly resolved vibronic bands are observed having the band origin of 33,791 cm(-1). The vibrational bands above the electronic origin were assigne d on the basis of the well-characterized electronic vibrational bands reported previously and of normal modes of vibrations derived by our H F/3-21G calculations.