Resonance enhanced multiphoton ionization spectroscopy of carbon disulphide

Rydberg excited states of the CS2 molecule in the energy range 56 000-81 000 cm(-1) have been further investigated via the two and three photon resonance enhancements they provide in the mass resolved multiphoton ionization (MPI) spectrum of a jet-cooled sample of a parent molecule. Spectral interpretation has been aided by parallel measurements of the kinetic energies of the photoelectrons that accompany the various MPI resonances. Thus we have been able to extend, and clarify, previous analyses of the tangled spin-orbit split vibronic structure associated with the (IIu)-I-3 and (IIu)-I-1 states derived from the configuration [(IIg)-I-2]4p sigma(u) and the (3) Delta(u), (1) Delta(u), and (1) Sigma(u)(+) states resulting from the configuration [(IIg)-I-2]4p pi(u), and to deduce an approximate wave number for the origin of the hitherto unidentified (3) Sigma(u)(+) state derived from this same configuration. Moving to higher energies we are able to locate, unambiguously, the origins of the next (n=5) members of four of these [(IIg)-I-2]np Rydberg series, and to identify extensive series based on the presumed Rydberg configurations [(IIg)-I-2]ns sigma(g) and [(IIg)-I-2]nf lambda(u) with, in both cases, n less than or equal to 10. We also identify MPI resonances attributable to CS(a(3)II) fragments, to ground state C atoms, and to S atoms in both their ground (P-3) and excited (S-1) electronic states. Analysis of the former resonances indicates that the CS(a(3)II) fragments resulting from two photon dissociation of CS2 at excitation wavelengths around 300 nm are formed with substantial rovibrational excitation. (C) 1996 American Institute of Physics.