Knowledge Bank

In a previous $paper1$, we reported for the first time a gas-phase infrared spectrum of $BH3$ through the $\nu 2$ band (out-of-plane bending) by infrared diode laser spectroscopy. The assignment was carried out for the qQ(J. K) branch with $K=J$ in the $1141cm-1$ region. In the present study, the spectrum of the $BH3\nu 2$ band was observed in the $900-1300cm-1$ region by a Fourier transform infrared spectrometer (Bruker 120 HR). The borane molecule was produced with a discharge in a $B2H6$ and *** mixture. The observed spectrum was analyzed by including the Coriolis interaction from the $\nu 4$ state to determine the molecular constants in the $\nu 2$ and $\nu 4$ states, where the ground state constants were fixed to those determined by the analysis of the $\nu 3$ $band2$. The band origins and the Coriolis coupling constant were $\nu 2=1147.4997(11)\nu 4=1196.460(61)$. and $D24=7.808(14)cm-1$. The previous Q-branch assignment of the diode laser $spectrum1$ was partly revised.