Probing argon–benzene van der Waals molecules and isotopically substituted benzene with laser-ionization mass spectrometry

Abstract

Ultrasensitive wavelength-dependent laser-ionization mass spectrometry is applied to spectroscopic studies of argon–benzene van der Waals molecules and isotopically substituted benzene molecules. Argon–benzene fragments either in its 1B2u excited electronic state or subsequent to being ionized. Substitution of a single 13C atom in the benzene monomer ring leads to an observable spectroscopic splitting whose magnitude can be accurately predicted from the 1B2u excited-state force field recently developed by Krogh-Jesperson et al. [ J. Phys. Chem.88, 5503 ( 1984)].