Rotational spectrum of ONCl in the (0, 0, 1) and (0, 1, 0) vibrational states and “ b” type spectrum in the ground state. Comparison of force field obtained by different combinations of experimental data

Abstract

From the rotational spectrum of ONCl in (0, 0, 1) and (0, 1, 0) excited vibrational states the inertia defects in these states have been determined. The “ b” type rotational spectrum in the ground state has also been measured allowing the determination of Δ 0 and of all the first-order centrifugal distortion constants. It is shown that by using differences of inertia defects Δ 2 and Δ 3 together with centrifugal distortion constants which do not involve the planarity relations and with harmonic vibrational frequencies of two isotopic species, the harmonic vibrational frequencies of two other isotopic species can be satisfactorily predicted. By using only inertia defects differences Δ 2 and Δ 3 as extra data, a definite choice can be made among the three sets of force constants which equally well reproduce the harmonic frequencies of four isotopic species.