Raman spectra from the internal vibrations of NH+4 ions in NH4Ag4I5

Abstract
The internal vibrations of NH+4 ions in the fast‐ion conductor NH4Ag4I5 have been studied by Raman spectroscopy. Bands due to the four normal modes of NH+4 have been observed along with some second order combination bands. The spectra are similar to those of the high temperature or α phase of NH4I, and at 17 K the spectra of NH4Ag4I5 resemble the spectra of supercooled α‐NH4I, or, more precisely, the spectra of a dilute solution of NH+4 in KI.