Excited states of pyrene excimer observed by photodissociation spectroscopy in a supersonic jet

The absorption spectrum of jet-cooled pyrene excimer was measured using photodissociation spectroscopy. Broad absorption bands were observed in the near-IR and visible regions, which were assigned to the B2u− ← B3g− and B2u+ ← B3g− transitions of the excimer, respectively. Excitation of these bands results in rapid dissociation of the excimer into monomer fragments, one of which is an electronically excited monomer in the S2 state. The formation mechanism of the pyrene excimer from the vdW dimer is also discussed.