Zero kinetic energy (ZEKE) photoelectron study of the benzene-N2 and fluorobenzene-N2 van der Waals complexes

The van der Waals (vdW) complexes of benzene and fluorobenzene with N-2 have been studied in a supersonic jet by using a zero kinetic energy (ZEKE) photoelectron technique combined with two-pulsed-field ionization (2PFI). ZEKE photoelectron bands due to the cation origin (D(0)0(+0)) were obtained via S(1)6(0)(1) and 0(0)(0) for benzene-N-2 and fluorobenzene-N-2, respectively. The lower limits of the adiabatic ionization energies of benzene-N-2 and fluorobenzene-N-2 are shifted by -27 and -62 cm(-1) from those of bare benzene and fluorobenzene, respectively. The cation origin bands of benzene-N-2 and fluorobenzene-N-2 are broad (FWHM: 35-50 cm(-1)), showing low-frequency structures with spacings of 6-9 cm(-1) probably caused by progressions of the vdW bending and torsion. (C) 1998 Elsevier Science B.V.