The Spectrum of the CN^{+} Molecule.

Abstract

The 1-6, 2-7, 1-7, and 2-8 emission bands of the F 2 A r-A 2 Jli transition of CN have been analyzed under high resolution. The following molecular constants have been determined for the F 2 A r state (cm" 1) : T e = 60095.64, B e = 1.3834, = 0.0187, D e = 7 X 10" 6 , c0e-1239.50, o)e%e 12.75. Some new band heads of the £ 2 2 +-A 2 IIt system are reported. During a recent investigation (Lutz 1971) of the emission spectrum of CN + , I observed a number of bands which were due to the neutral CN molecule. In particular, between 2350 and 2550 Â I found five red-degraded bands each of which consists of two subbands with heads separated by 110 cm-1. By comparison with the CN emission spectrum of Douglas and Routly (1955), these bands were readily identified as the 0-5, 1-6, 2-7, 1-7, and 2-8 bands of the F 2 A r-^4 2 IL transition. Although Jha and Rao (1966) observed these bands under low resolution, the rotational fine structure of only the 0-2 and 0-3 bands has been analyzed (Douglas and Routly 1955). Figure la of Douglas and Routly's paper shows the 0-3 band. Since it is of some interest to know the rota-tional and vibrational constants of = 1 and 2 of F 2 A r , I have analyzed the 1-6, 2-7, 1-7, 2-8 bands and present my results here. The experimental details are found elsewhere (Lutz 1971). The analysis of these bands was straightforward. The wavenumbers and the assignments of the lines are given in Table 1. Effective B values were obtained from the AiF(/) values since the F-branches were too weak to use. The band origins were determined from Qn(J) + Q