Spectroscopic properties of jet-cooled methanol clusters, n=1–6, attached to perylene

Supersonically cooled clusters of perylene/(CH3OH)n (n=1–6) have been studied using resonance-enhanced near-threshold two-photon ionization followed by time-of-flight mass-spectrometry. The perylene S0→S1 transition is displaced to lower energy in all cases, but the amount of the displacement varies irregularly with cluster size over ≈150 cm−1. Much greater variations are observed in the threshold ionization energy, over a range >3000 cm−1.