OBSERVATION OF A NEAR-IR ABSORPTION-BAND OF THE FLUORENE EXCIMER BY PHOTODISSOCIATION SPECTROSCOPY

Photodissociation behaviors of the fluorene excimer, produced from the electronic excitation of the corresponding van der Waals dimer, have been investigated by photodepletion and photofragmentation techniques. The excimer exhibits a strong absorption band in the near-IR region, with an intensity maximum at about 850 nm. This excimer absorption is assigned to an intervalence transition between the lowest excimer state and an upper state of repulsive character, both arising from the exciton resonance interaction of the monomer S1 state. Excitation of this band leads to a rapid dissociation of the excimer into monomer fragments, one of which is electronically excited. The photodissociation dynamics of the fluorene excimer is compared with that of the naphthalene excimers.