A REMPI study of indene and its clusters with argon and krypton

The S₀ → S₁ transition of indene was studied in a supersonic jet by resonance enhance multiphoton ionization and assigned with the help of an ab initio calculation. Experimental results are also reported for argon and krypton clusters of indene, from which the dissociation energies of the 1:1 clusters were estimated in both S₀ and S₁ states. Two-color two-photon ionization spectroscopy was used to determine the ionization potential and dissociation energy of the indene-argon cluster ion. The data are compared with results obtained for styrene, whose electronic structure is similar, but has much lower frequency out-of-plane vibrational modes.