The Band Spectra of SbF and BiF

New band spectra attributed to the molecules SbF and BiF have been excited by active nitrogen. The spectrum of SbF from 2000-5500A is found to have three groups of bands lying in the regions 3600-5200A, 2600-2700A and 2200-2430A. Analysis of the first group shows that sixty-one bands out of sixty-nine can be placed into two systems with the following vibrational constants, in ${\mathrm{cm}}^{-1\mathrm{}}$:— The second group consists of a few isolated bands degraded to shorter wave-lengths and the third of bands in closely spaced sequences and also degraded to shorter wave-lengths. A preliminary analysis indicates that the bands in the latter group can be placed into two systems for which $\omega _e^{}{}_{}{}^{\prime }\sim 700$ ${\mathrm{cm}}^{-1\mathrm{}}$, $\omega _e^{}{}_{}{}^{\prime \prime }\sim 620$ ${\mathrm{cm}}^{-1\mathrm{}}$ and $\Delta {\nu }_{21}\sim 1850$ ${\mathrm{cm}}^{-1\mathrm{}}$. Three new systems of bands, degraded to shorter wave-lengths and forming a triplet system with wide multiplet separations, (7330 ${\mathrm{cm}}^{-1\mathrm{}}$ and 4800 ${\mathrm{cm}}^{-1\mathrm{}}$), are found in the spectrum of BiF at 3050-3250A, 2650-2850A and 2250-2350A. Photographs taken with small dispersion indicate that $\omega _e^{}{}_{}{}^{\prime }\sim 620$ ${\mathrm{cm}}^{-1\mathrm{}}$ and $\omega _e^{}{}_{}{}^{\prime \prime }\sim 520$ ${\mathrm{cm}}^{-1\mathrm{}}$.