Rotational spectra and molecular structures of ArHBr and KrHBr

Abstract

Rotational spectra have been observed for four isotopes of ArHBr and ArDBr and eight isotopes of KrHBr and KrDBr using a Fabry–Perot Fourier transform spectrometer with a pulsed supersonic nozzle as the molecular source. The rotational constants in the ground vibrational state ?₀ with their centrifugal distortions D_J, as well as Br nuclear quadrupole coupling constants χ_a, are given. In addition, an important centrifugal distortion of the Br quadrupole coupling constant, D_χ, an indicator of the coupling between the radial and angular potentials, is given for ArHBr and KrHBr. The Br spin–rotation interaction c in ArHBr is also obtained. The results are: The molecular structures are consistent with a linear equilibrium geometry with the H(D) atom located between Br and the rare gas atoms. The complexes undergo large amplitude vibrations and estimates of the bending and stretching force constants and frequencies are given. By combining the bending, stretching, and their coupling, we have obtained the harmonic bending and stretching force constants (k_s1 and k_b1) and 6/12 Lennard‐Jones potential parameters (ε and R_e) for ArHCl, KrHCl, ArHBr, KrHBr.