The photodissociation of size-selected benzene cluster ions, (C 6H6 )+m + hω→ (C 6H6 )+n + (m - n) C 6H6, has been investigated in the 410-750 nm wavelength range using tunable dye laser radiation. The measurements were performed using a tandem mass spectrometer [a linear time-of-flight (TOF)/reflectron TOF] combined with multiphoton ionization (MPI) for ion preparation. Only C 6H6+ was detected as a photofragment of (C 6H6)2+ and (C6H 6)3+, while both C6H 6+ and (C6H6)2 + fragments were observed in the case of (C6H6 )4+ photodissociation. Photodissociation spectra, i.e., photofragment yield spectra as a function of wavelength, of (C6H 6)+m (m = 2,3) were obtained. Two local excitation bands of (C6H6)+m were seen in this region and assigned to the C(A2u) ← X(E 1g ) and the B(E2g) ← X(E1g) transitions of a C6H6+ unit in the clusters. The origin of the B←X transition of (C6H6)2+ and (C6H6)3+ was redshifted relative to that of C6H6+ by about 1400 and 2400 cm-+, respectively, while the C←X bands of (C6H6) 2+ and (C6H6 )3 + were seen at the same wavelengths of 440 nm. Possible structures for the cluster ions are discussed based on the spectral shifts.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry