Global Rovibrational Analysis of HCCNC Based on Infrared and Millimeter-Wave Spectra

Abstract

New microwave and millimeter-wave spectra up to 200 GHz of isocyanoacetylene (HCCNC) have been recorded. About 675 lines have been assigned to 111 vibrational states with energies up to 1700 cm−1. In previously recorded infrared spectra in the 600–2000 cm−1 domain, 53 new infrared bands have been assigned and analyzed. These concern upper vibrational states up to energies close to 1900 cm−1, which are combinations of the three bending modes (ν5 to ν7) and the lowest energy stretching mode ν4. The assignments were made possible thanks to a global rovibrational analysis progressively applied to all available data. Good agreement has been obtained, and a set of 155 molecular parameters has been determined. Our analysis suggests that the term directly coupling 2ν6 and ν5 + ν7 states (k5667) is to be added to our model, and also Coriolis interactions between ν6 and 2ν7 states on one hand, and between ν5 and ν6 + ν7 states on the other hand.