Long-Range Order in NH4Cl

Abstract

Small-angle optical harmonic scattering in N${\mathrm{H}}_4$Cl reveals the presence of long-range, macroscopic order well above the transition temperature, $T_{\lambda }=242.6\mathrm{}°$K, for orientational disordering of the N${\mathrm{H}}_4^{+}$ ions.