ZERO KINETIC-ENERGY PHOTOELECTRON STUDY OF THE NAPHTHALENE-AR VAN-DER-WAALS COMPLEX

The naphthalene-Ar van der Waals complex formed in a supersonic jet ex pansion was studied. Mass-selected multiphoton ionization and zero kin etic energy (ZEKE) photoelectron spectra obtained in the two-color (11') ionization scheme are reported. The S-1-S-0 O-0(0) transition in t he complex is red-shifted by 15 cm(-1) and its adiabatic ionization en ergy is 65607 cm(-1) (+/-3 cm(-1)), 85 cm(-1) lower than that of bare naphthalene. Ab initio calculations at the level of second order Molle r-Plesset theory give a potential energy minimum for the Ar atom at th e distance of 3.4 Angstrom above the center of symmetry of naphthalene and the binding energy of 430 cm(-1) for the neutral complex.