Knowledge Bank

High resolution spectra have been recorded of the $\nu 5$ bands of $\mathrm{<mrow\; data-mjx-texclass="ORD">10</mrow>}BH3CO$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">11</mrow>}BH3CO$ which occur around $2450cm-1$ with a resolution of about $0.03cm-1$. Even under a lower resolution these bands appear to be complicated; these complications arise from the presence of “hot” bands due to $\nu 5+\nu 8-\nu 8$ and also from a Fermi resonance between the $(\nu 5=1)$ and $(\nu 2=\nu 8=1)$ levels, both of which have E vibrational symmetry. Many of the K subbands have been analyzed and these results, which will be discussed, have been used not only to obtain good rotational constants but also to further our understanding of these bands.