Pressure and temperature dependence of the nuclear quadrupole resonance of 35Cl in chloracetamide

Abstract

The 35Cl NQR frequency in chloracetamide has been studied at pressures up to 2.5 kbar and in the temperature range 77–308 K. The experimental results were analyzed applying the method of Kushida, Benedek, and Bloembergen (KBB). The KBB theory was found to be fulfilled in chloracetamide only at temperatures below about 240 K. Above 240 K, deviations from the KBB theory may be a result of large anharmonicity of the molecular vibrations. These data correlate with the temperature dependence of the thermal expansion coefficient, which shows an exponential increase above 240 K. Possible reasons for the limited applicability of the KBB theory are discussed.