Description:
Rotational transitions of the HBF+ ion were observed in the region up to 380 GHz by using a source-modulated microwave spectrometer combined with a hollow cathode free space cell. The HBF+ (or DBF+) ion was generated by a dc discharge in a mixture of BF3 and H2 (or D2). The ion was identified on the basis of the linear-molecule spectral pattern with the nuclear hyperfine structure of the boron nucleus, supported by the spectral-intensity lowering by an external magnetic field. The rotational constant, the centrifugal distortion constant, and the nuclear quadrupole coupling constant were precisely determined for three isotopic species: H11BF+, H10BF+, and D11BF+. From the observed ground-state rotational constants the combined rs parameters were obtained; rs(BH) =1.173 47(2) Å and rs(BF) =1.210 28(2) Å.