The direct<i>l</i>-type resonance spectrum of CF³⁵₃Cl in its vibrational state<i>v</i>₆= 1

Abstract

Using the technique of Fourier transform microwave spectroscopy about 100 direct l-type resonance transitions for CF35 3Cl in the first excited state of the doubly degenerate vibration v 6 have been observed in the range of 2–18 GHz. These transitions are observable due to a mixing of states with Δl = Δk = ±2 by the l-type (2, 2) interaction. In addition to the (2, 2) interaction it was necessary to include two further off-diagonal contributions to explain the spectrum: the (2, -4) interaction, which contributes to the splittings of the transitions with G = |k - l| = 3, and either the (2, -1) or the (0, 3) interaction corresponding to two different reductions of the effective Hamiltonian. The unitary equivalence of both sets of parameters has been demonstrated. The transitions show hyperfine splittings owing to quadrupole rotation-vibration interactions. In a simple approach the theory of Aliev and Hougen has been applied to explain the hyperfine structure patterns and to determine the (2, 2) quadrupole l-type resonance parameter x 6. Some features of direct l-type resonance spectra are discussed.