Protonation and multi-hydrogenation of benzophenone (BP) in BP/toluene and BP/ethanol binary cation clusters

Formation mechanisms of protonated benzophenone (BP) were investigated in BP/toluene(Tol) and BP/ethanol(EtOH) binary cation clusters by a resonant enhanced multiphoton ionization (REMPI) time-of-flight mass spectrometry. [(BP)H]+ and [(BP)2H]+ are produced by intracluster ion–molecule reactions after REMPI of Tol via the S1 or BP via the Sn in BPn(Tol)m clusters. In a BP/EtOH system, [(BP)H(EtOH)n]+ are generated after the REMPI of BP and undergo hydrogenation in the aromatic rings by the subsequent photoexcitation. The dominant products are [(BP)H3(EtOH)n]+ and [(BP)H8(EtOH)n]+, which appear in smaller and larger clusters, respectively. Structures of protonated BP’s and intracluster reactions were discussed based on quantum chemical calculations.