THZ ROTATIONAL SPECTRA OF HBR ISOTOPOMERS IN THEIR V=0,1 STATES

We have observed the pure rotational spectra of HBr isotopomers in the ir v = 0 and v = 1 states between 0.97 and 1.02 THz, i.e. the HBr J = 2 - 1 and the DBr J = 4 - 3 transitions, respectively. In the analysis , all presently available rotational transitions of all isotopomers ha ve been fitted to a Dunham-type Hamiltonian to obtain the isotopically invariant parameters, including vibrational and rotational expansion coefficients for the hyperfine constants. In the analysis, the vibrati onal expansion coefficients of the nuclear quadrupole interaction are determined up to second order, and up to first order for the nuclear s pin-rotation interaction.