EPR Observations of Positional Disorder of the [(CH₃)₃NH]⁺ Ions in [(CH₃)₃NH]CdCl₃

Two chemically inequivalent [N(CH₃)₃]⁺ radical species produced via γ-irradiation were detected by EPR in the low-temperature, orthorhombic 1 x √3 phase of [(CH₃)₃NH]CdCl₃. This indicates a twofold, static disorder of the [(CH₃)₃NH]⁺ (TrM) ions. One of the radical species could be identified as originating from the “normal” TrM ions and the other from the “disordered” TrM ions. The EPR result also indicates that the population ratio of the “disordered” TrM ions relative to the “normal” TrM ions is temperature dependent; this ratio decreases with decreasing temperatures.