MULTIPHOTON IONIZATION SPECTROSCOPY OF NITRIC OXIDE

Abstract

The three- and four-photon ionization spectrum of nitric oxide gas has been observed using a nitrogen-pulsed tunable dye laser and a simple proportional counter operating as a current detector. The photo-ionization cross-section is dominated by two- and three-photon transitions to resonant intermediate states and the spectrum yields the multi-photon absorption spectrum of those states. The complex rotational structure will be discussed and a comparison with the one-photon spectrum will be presented.