Analysis of incommensurate structure in [N(CH3)(4)](2)ZnCl4 crystal

We analyzed the temperature dependence of the amplitude of modulated struct ures of [N(CH3)(4)](2)ZnCl4 crystal in the incommensurate (INC) phase by me asuring the EPR spectra for Mn2+ doped single crystal. The amplitude of the vibrational modulation linearly increased with decreasing temperature. App lying Frank and Van der Merwe model, we simulated the EPR spectra in the IN C phase. The simulated spectra agreed with the observed one very well. We, therefore, revealed that the vibrational modulation in this INC phase is du e to the interaction between the harmonic chain of inter-particles and the modulation due to underlying potential which comes from the commensurate st ructure.