Rotational spectrum of HCBr produced by 193-nm laser photolysis of bromoform

The pure rotational spectrum of bromomethylene (HCBr) was studied by kinetic microwave spectroscopy between 420 and 472 GHz. The HCBr radical was produced by 193-nm ArF laser photolysis of bromoform (CHBr3). More than 130 rotational transitions for both (HCBr)-Br-79 and (HCBr)-Br-81 species in the ground vibrational state were measured involving 1 less than or equal to J less than or equal to 33 and 0 less than or equal to K-a less than or equal to 5. The spectra were well described by an S-reduced Watson Hamiltonian in the I-r representation including the nuclear quadrupole and spin-rotation hyperfine terms. Rotational, centrifugal distortion, Br-79,Br-81 nuclear quadrupole and spin-rotation coupling constants were derived for both (HCBr)-Br-79 and (HCBr)-Br-81 species in the ground vibrational state. (C) 2003 Elsevier Science (USA). All rights reserved.