HIGHLY EXCITED-STATES OF NITRIC-OXIDE STUDIED BY HIGH-RESOLUTION RESONANCE-ENHANCED MULTIPHOTON IONIZATION SPECTROSCOPY

Two-photon transitions A 2-SIGMA+ (upsilon' = 0)-X 2-PI-(upsilon" = 0) of nitric oxide are investigated by high-resolution resonance-enhanced multiphoton ionization spectroscopy. The underlying causes behind observed anomalous intensity features of these two-photon transitions are discussed. Several new lines produced by the three-photon transitions "L 2-PI-(upsilon = 4)-C 2-PI-(upsilon = 6)"-X 2-PI-(upsilon = 0) and K 2-PI-(upsilon = 1)-X 2-PI-(upsilon" = 0) are assigned. The values for T-upsilon and B-upsilon of the K 2-PI-(upsilon = 1) state are determined. The ALPHA doublet at 66350 cm-1 has been resolved. It is suggested that several lines with anomalous intensity on the O-12 branch of the A 2-SIGMA+ (upsilon' = 0)-X 2-PI-(upsilon" = 0) band should be interpreted as the result of an autoionization process rather than as the result of an accidental resonance of a third photon with rotational levels of the "L 2-PI-(upsilon = 4)-C 2-PI-(upsilon = 6)" state as previously has been anticipated.