Infrared emission spectroscopy and ab initio calculations on VCl

The emission spectrum of VCl has been investigated at high resolution in the 3000-19 400 cm⁻¹ region using a Fourier transform spectrometer. The bands were excited in a high temperature carbon tube furnace by the reaction of vanadium metal vapor and a trace of BCl₃ as well as in a microwave discharge lamp by the reaction of VOCl₃ vapor with active nitrogen. The spectra were recorded using the Fourier transform spectrometer associated with the McMath-Pierce telescope of the National Solar Observatory at Kitt Peak. The analysis of the system of VCl (previously labeled as ) has been extended by analyzing the rotational structure of some additional bands. A rotational analysis of the , , and subbands of the 0-2, 0-1, 0-0, and 1-0 bands, and the subband of the 0-1 and 0-0 bands has been obtained and molecular constants have been extracted. The subband was not identified in any of the assigned bands. The spectroscopic properties of the low-lying electronic states of VCl have been predicted by CASSCF/CMRCI ab initio calculations and the experimental assignments are supported by the ab initio results.