Abstract
14N NQR frequencies, linewidth, and spin–lattice relaxation times were measured in s-triazine as a function of temperature between 77 and 280 °K. The second order phase transition from hexagonal to monoclinic which takes place at the critical temperature Tc=198.8 °K was studied in detail. The splittings of the NQR lines in the monoclinic phase, which are proportional to the order parameter, were found to vanish with the critical exponent β=1/2 on approaching Tc. Above 210 °K the temperature dependence of the linewidth and of the spin–lattice relaxation time indicates that the s-triazine molecule undergoes molecular reorientation around its threefold axis. The activation enthalpy for this motion was found to be ΔH=14.0 kcal/mole. These relaxation phenomena were analyzed using a density matrix formalism. Explicit expressions for the decay exponents and signal function were derived.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
