Experimental observation and quantum chemical characterization of the S1 ← S0 transition of protonated naphthalene-argon clusters.

We report on the photodissociation spectrum of protonated naphthalene(+)-argon complexes (NpH(+)-Ar) recorded by excitation into the first excited singlet electronic state. Unlike previous electronic spectra of the free molecule (NpH(+)), both the α and the β isomer could be observed for the Ar adducts. Detailed information on the S0 and S1 state of both isomers is provided by quantum chemical calculations. An assignment of observed vibrational bands is proposed based on Franck-Condon simulations.