Measurements on Higher J Rotational Lines of Vibration Rotation Bands and Study of Resonances in Linear Polyatomic Molecules I ν_2 and 2ν_2^0 Bands of HC^12N†

The ν2 and the 2ν20 bands of the HC12N molecule have been measured with a vacuum grating spectrometer and the molecular constants evaluated. Observations on the ν2 band have been carried out to J=40 and the data did not reveal any necessity for introducing an H term in the expression for the rotational term value. The anomalous centrifugal distortion constant observed for the 2ν20 band has been discussed in the light of current theories. The difference bands 3ν21−ν21(c) and 3ν21−ν21(d) have been identified in the region of absorption of the 2ν20 band.