ELECTRONIC SPECTROSCOPY OF THE C STATE OF NO BY LASER MULTIPHOTON IONIZATION - ROTATIONAL STRUCTURE OF THE C-2-PI(V'=0)[-X-2-PI(V''=0) 2-PHOTON BAND

Rotationally resolved two-photon electronic spectra of nitric oxide (N O) on the (CII)-I-2(v' = 0) <-- (XII)-I-2(v '' = 0) transition have be en recorded in the near-UV between 384nm and 375mn by the (2 + 1) REMP I technique. The REMPI spectra of the delta(0,0) band have been measur ed and assigned for jet-cooled NO, NO at room temperature and for the nascent, highly rotationally excited NO formed by the UV-photodissocia tion of nitrosyl chloride (CINO) in a one-colour dissociation-probe ex periment. The wavelengths of all major rovibronic transitions have bee n measured accurately using optogalvanic spectroscopy and interference fringe counting as a calibration technique. The unperturbed transitio ns have been fitted to term values up to J = 53.5 with rotational ener gies in excess of 4000 cm(-1) to a single algebraic energy formula. Th e absence of certain ii-doubled sub-branches in the spectra has been e xplained by different virtual two-photon routes via the electronic A s tate as the intermediate level. In connection with a discussion of two -photon parity selection rules and rotational line strengths we have s hown that (2 + 1) REMPI spectroscopy of the C <-- X transition on the delta(0,0) band will permit convenient and reliable measurements of th e rotational and fine-structure populations of most, if not all levels of NO X (v = 0).