Rotationally resolved infrared absorption spectrum of N-4(+)

The rotationally resolved infrared band of the antisymmetric stretching vibration (nu(3)) of N-4(+) has been recorded by tunable diode laser spectroscopy. A continuous supersonic expansion of pure nitrogen through a slit nozzle and electron impact ionization was employed. Forty-four P and R branch transitions with J up to 25 are observed. The band origin is at nu(0)=2234.5084(4) cm(-1) and the rotational constants are determined to be B-0=0.112 05(3) cm(-1) and B-1=0.111 76(3) cm(-1). The infrared spectrum shows that N-4+ has a linear ground state structure. (C) 1996 American Institute of Physics.