Raman Spectra of the Alkali Azides: K${\mathrm{N}}_3$, Rb${\mathrm{N}}_3$, Cs${\mathrm{N}}_3$

The first-order Raman spectra of K${\mathrm{N}}_3$, Rb${\mathrm{N}}_3$, and Cs${\mathrm{N}}_3$, all of which possess a body-centered tetragonal crystal structure with the symmetry of the space group $\frac{D_{4h}^{18}-I4\mathrm{}}{\mathrm{mcm}}$, have been measured at room and liquid-nitrogen temperatures. The five Raman-active phonons predicted by group theory have been observed and assigned on the basis of the scattering tensors.