Infrared–microwave double resonance spectroscopy of the ν3 band of BF3 using a tunable diode laser

Abstract

Pure rotational transitions allowed by vibrationally induced dipole moment are observed in the ν₃ state (E’) of ¹⁰BF₃ by infrared–microwave double resonance using a tunable diode laser. The observed rotational transitions are analyzed simultaneously with the infrared vibration–rotation transitions and pure rotational transitions in the ground state to obtain the molecular constants for the ground and ν₃ states. The C₀ and D_K constants are determined to be 0.172 165 83(8) and 0.3526(14)×10⁻⁶ cm⁻¹, respectively. Rotational transitions in the ν₃ state of ¹¹BF₃ reported previously are also analyzed with infrared vibration–rotation transitions including the Fermi resonance with 3ν₄.