Studies of Ar:HBr using fast scan submillimeter-wave and microwave coaxial pulsed jet spectrometers with sub-kHz precision

Coaxial pulsed jet submillimeter spectra are reported for Ar:H79Br and Ar:H81Br transition frequencies measured with sub-kHz precision. This is confirmed by comparing combination frequency differences associated with ΔF=+/−1 hyperfine components in the rovibrational transitions of the low frequency Σ bending mode with corresponding sum frequencies of the rotational transitions in the ground state precisely measured with a pulsed-nozzle FT microwave spectrometer (1.5 kHz resolution, 200 Hz accuracy). Ground state molecular parameters evaluated using the submillimeter-wave and microwave techniques are demonstrated to have comparable accuracy. Furthermore, excited Σ state molecular constants for the isotopic band origins of Ar:H79Br and Ar:H81Br at 329 611.4284(10) and 329 225.6778(10) MHz are shown to be determined with equivalent accuracy.