THE GAMMA (A(2)SIGMA(-X(2)PI(R)) SYSTEM OF THE NITRIC-OXIDE ISOTOPOMERS())

The gamma (A(2) Sigma(+)-X(2) Pi(r)) system of the nitric oxide isotop omers (NO)-N-14-O-16, (NO)-N-15-O-16, (NO)-N-14-O-18 and (NO)-N-15-O-1 8, excited in the anode glow of a two-column hollow-cathode discharge tube, was recorded in the spectral region 2140-2730 Angstrom under med ium resolution. The gamma system of (NO)-N-15-O-18 and several bands o f (NO)-N-14-O-18 of this system in emission are reported here for the first time. The rotational structure of the 0-1, 0-2, and 0-3 bands of (NO)-N-15-O-18 of this system was also recorded under high resolution . The wavenumber data of these three electronic bands and those of the infrared vibration-rotation absorption bands 1-0, 2-0, and 3-0 of the X(2) Pi(r) state of (NO)-N-15-O-18 available from the literature were together used in a global fit, using an effective Hamiltonian method for the (2) Pi state, and molecular constants were derived for the A a nd X states. These include the following (in units of cm(-1)) for stat e A of (NO)-N-15-O-18: T-0 = 44 130.244(2), B-0 = 1.812980(7), and D-0 = 4.694(6) X 10(-6). The present work suggests that the X(2) Pi(r) st ate changes from Hund's case (a) at lower J to case (b) at higher J. F rom the measured bandhead data the vibrational constants of the X and A states of (NO)-N-14-O-16, (NO)-N-15-O-16, and (NO)-N-14-O-18 were al so determined. (C) 1996 Academic Press, Inc.