Negative ENDOR study of an irradiated single crystal of triglycine sulfate and its ferroelectric phase transition

摘要

With the use of the negative ENDOR technique an xhyphen;ray irradiated crystal of triglycine sulfate was studied over the temperature range from 170 to 420 K (Tc=322 K). Within the 11ndash;17 MHz frequency range, signals from more than four different types of protons were detected. Each of these proton signals including the one from H7is a singlet whenTgsim;Tc, while the signal splits into a double whenTTc. Although the splitting depends on temperature, no evidence for line broadening was detected. This temperature behavior was explained in terms of a simple quantumhyphen;tunneling process, the exchange integral (Ggr;) of which was estimated to be 102cmminus;1in order of magnitude.