The Near Infra-Red Spectrum of Water Vapor. Part I. The Perpendicular Bandsν2and2ν2

The rotation-vibration bands in the water vapor spectrum lying in the bolometric infra-red have been completely remeasured. In this paper the measurements are reported on the bands ${\nu }_2$ and $2{\nu }_2$. An analysis of the complicated rotational structure has been carried out. From the interpretation of the data the value of the normal frequency ${\nu }_2$ and the anharmonic constant $U_{22}$ have been calculated as well as the values of the moments of inertia effective in these two vibration states. The frequency ${\nu }_2$ is found to take the value 1653.8 ${\mathrm{cm}}^{-1\mathrm{}}$ and the anharmonic constant $U_{22}=-19.25\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$. For the states ${\nu }_2$ and $2{\nu }_2$ the effective moments of inertia take the values ${I_x}^{\mathrm{}\left(e\right)\mathrm{}}=0.905\mathrm{}\times {10}^{-40\mathrm{}}$ g ${\mathrm{cm}}^2$, ${I_y}^{\mathrm{}\left(e\right)\mathrm{}}=1.902\mathrm{}\times {10}^{-40\mathrm{}}$ g ${\mathrm{cm}}^2$, ${I_z}^{\mathrm{}\left(e\right)\mathrm{}}=3.054\mathrm{}\times {10}^{-40\mathrm{}}$ g ${\mathrm{cm}}^2$ and ${I_x}^{\mathrm{}\left(e\right)\mathrm{}}=0.775\mathrm{}\times {10}^{-40\mathrm{}}$ g ${\mathrm{cm}}^2$, ${I_y}^{\mathrm{}\left(e\right)\mathrm{}}=1.895\mathrm{}\times {10}^{-40\mathrm{}}$ g ${\mathrm{cm}}^2$, ${I_z}^{\mathrm{}\left(e\right)\mathrm{}}=3.095\mathrm{}\times {10}^{-40\mathrm{}}$ g ${\mathrm{cm}}^2$, respectively. The values arrived at for the above constants serve to confirm the theory of the water vapor molecule.