Laser excitation spectroscopy of the (A)over-tilde (3)Pi(u)-(X)over-tilde (3)Sigma(g)(-) transition of the NCN radical .1. The (0-0) band

The (0-0) band of the <(A)over tilde (3) Pi(u)>-<(X)over tilde (3) Sigma(g)(-)> transition of the NCN radical at 329 nm has been re-examined at Doppler limited resolution by laser excitation spectroscopy. The molecule was generated in a microwave discharge through N-2 and CF4 in helium. The previous analysis by Herzberg and Travis (Can. J. Phys. 42, 1658-1675 (1964)) has been confirmed and extended to give considerably improved values of the molecular parameters. The major constants are determined to be <(A)over tilde (3) Pi(u)> T-0 = 30383.96706(49) cm(-1) A(0) = -37.56664(60) cm(-1) B-0 = 0.3966452(87) cm(-1) r(0) = 0.1231886(14) nm <(X)over tilde (3) Sigma(g)(-)> B-0 = 0.3972522(87) cm(-1) r(0) = 0.1230944(14) nm lambda(0) = 0.79420(50) cm(-1) gamma(0) = -0.001175(19) cm(-1). (C) 1996 Academic Press, Inc.