Infrared and Raman spectra of lithium and ammonium nitrate solutions in liquid ammonia

Vibrational spectra, most of them obtained from Raman scattering, are reported for LiNO₃ and NH₄NO₃ solutions in liquid ammonia, ranging from dilute to the compositions LiNO₃/1.6NH₃ and NH₄NO₃/1NH₃. All the spectra were obtained from solutions at ambient temperatures. Large changes in the $\mathrm{N–H}$ stretching region are correlated with the effects of the electrolytes on the solvent structure. Low‐frequency bands associated with ${\mathrm{Li–NH}}_3$ modes are identified. Spectral features indicative of both solvent‐separated and contact ion pairs involving Li⁺ and ${\mathrm{NO}}_3^{-}$ are analyzed. Contact ion pairing between ${\mathrm{NH}}_4^{+}$ and ${\mathrm{NO}}_3^{-}$ ions in this solvent fails to produce any measurable splitting of the ${\mathrm{NO}}_3^{-}{\mathrm{\hspace{0.17em}\nu }}_3\mathrm{(E\prime )}$ or ν₄(E′) modes.