FOURIER-TRANSFORM EMISSION-SPECTROSCOPY OF THE A(6)SIGMA+-X(6)SIGMA+ SYSTEM OF CRH - EVIDENCE FOR A (4)SIGMA+ LOWEST EXCITED-STATE

The emission spectrum of CrH has been observed in the near-infrared region from 10 000-13 500 cm-1 using a Fourier transform spectrometer. Compared with the previous work on this molecule, the present spectra provide greatly improved measurements of the line positions of the A6Σ+-X6Σ+ electronic transition. The rotational analysis of the 0 - 0 band has been performed providing the following principal molecular constants: T00 = 11 552.6848(10) cm-1, B′ = 5.271996(29) cm-1, and B″ = 6.1317406(19) cm-1. As was first noted by Kleman and Uhler, the excited state is perturbed. By correcting a few misassignments in the previous work, we conclude that a nearby a4Σ+ state is responsible for the perturbation. The a4Σ+ state has an approximate band origin T00 = 11 186 cm-1 and a preliminary rotational constant B0 = 6.10 cm-1. This state lies below the A6Σ+ state and is, therefore, the lowest lying excited state. © 1993 Academic Press, Inc.