Microwave spectra of nitryl fluoride in excited vibrational states and its application to vibrational assignment

Abstract

Microwave spectra of nitryl fluoride in the v 3 = 1 and v 6 = 1 states were identified. The rotational constants, vib-rot interaction constants and inertia defects in these states were determined. Large inertia defects and large vib-rot interaction constants α C and their signs in the excited vibrational states indicate that the ν 3 and ν 6 vibrations are nearly degenerate and further that the frequency of ν 3 is larger than that of ν 6. The inertia defects were combined with the calculated Coriolis coupling constants to estimate the frequency difference ν 3 - ν 6 = 8 cm −1, which gave a definite discrimination among possible assignments of fundamental frequencies already proposed.