The Infra-Red Spectrum and Molecular Constants of Carbon Monoxide

The fundamental and first overtone bands of carbon monoxide have been measured under high resolution and the lines in the positive and negative branches in both bands have been fitted to formulae of the form $\nu =a+bm+c{m}^2+d{m}^3.$ The molecular constants ${\nu }_0$, $I_0$, $B$ and $C$ as defined by Colby depend directly on the constants $a$, $b$, $c$, $d$ and have been determined from these measurements. Their values are ${\nu }_0=2168.48\mathrm{} {\mathrm{cm}}^{-1\mathrm{}}, I_0=1.429\mathrm{}\times {10}^{-39\mathrm{}} \mathrm{g} {\mathrm{cm}}^2, B=1.38\mathrm{}\times {10}^{-6\mathrm{}},C=\mathrm{6.202.}\mathrm{}$ The constants used in electronic work, as defined by Jevons, have also been computed and are in close agreement with previous results.