Bandwidths studied as a function of temperature in ammonium halides near Tλ

This study gives our analysis of the Raman bandwidths using the soft mode-hard mode coupling model applied to ammonium halides. The temperature dependence of our observed bandwidths for the ν5(174 cm−1) Raman mode of NH4Cl and ν5(177 cm−1) Raman mode of NH4Br, is analyzed close to phase transitions. From our analysis, we obtain β = 0.13 as the values of the critical exponent for the order parameter in the first order phase region for the ammonium halides.