AbstractThe weaker spectral features in the Raman spectra of MN3(M = K, Rb, Cs) in the region 1240–1360 cm−1are reported. The present study indicates that the two‐phonon modes involving ν2can be analysed solely in terms of k = 0 selection rules whilst the two‐ and three‐phonon bands involving internal and external combination modes require a critical point analysis. There are several possible assignments of a multiphonon band of the latter type; its appearance apparently depends on proximity to an intense fundamental mode, from which it presumably steals