Cavity ring-down overtone spectroscopy of HCN, H13CN and HC15N

This paper reports the results of our use of Cavity Ring Down Spectroscopy to extend the study of highly excited vibrational states in HCN. We extend our previous study of the HCN isotopomer, reporting on some weaker bands between 17 500 and 19 500 cm. We also report spectra of overtone and combination bands with six, seven, and eight quanta of stretching vibration in the isotopomers HCN and HCN in the interval from 17 500 to 23 000 cm. The observed spectroscopic constants and band intensities are compared with calculated values. All but one of the observed bands can be fit to within experimental accuracy (;0.02 cm) to the standard distortable–rotor Hamiltonian. The one perturbed band has been successfully analyzed in terms of three anharmonically coupled levels. An anomalous line intensity distribution has been observed in the 115 and 016 P←S bands, which we believe is produced by Coriolis coupling. © 1995 American Institute of Physics.