Raman spectra of gaseous C${\mathrm{O}}_2$, ${\mathrm{N}}_2$O, N${\mathrm{H}}_3$, C${\mathrm{H}}_4$ and ${\mathrm{C}}_2$${\mathrm{H}}_4$ have been photographed using the line $\lambda 2536$ of mercury as the exciting radiation. Vibrational transitions have been observed in all the gases investigated, and rotational transitions in the cases of N${\mathrm{H}}_3$ and C${\mathrm{H}}_4$. For the frequency shifts due to the vibrational transitions, the following numerical values (in ${\mathrm{cm}}^{-1\mathrm{}}$) have been found:

Raman spectra of liquid N${\mathrm{H}}_3$ have been photographed and found to give the two frequency shifts: 3298.4 and 3214.5. In the case of gaseous N${\mathrm{H}}_3$, pure rotational transitions lead to a moment of inertia having the value $I_0=2.79\mathrm{}\times {10}^{-40\mathrm{}}$. In the case of methane, the positive and negative branches of the 3022.1 band lead to the value $I_0=5.17\mathrm{}\times {10}^{-40\mathrm{}}$. The relations between these data and infra-red absorption data are discussed.

• Received 15 July 1929

DOI:https://doi.org/10.1103/PhysRev.34.582