| Co-Investigator(Kenkyū-buntansha) |
NAGASAWA Isoroku Department of Chemistry, University of Tsukuba, Assistant, 化学系, 助手 (40302351)
ISHIMARU Shin-ichi Department of Chemistry, University of Tsukuba, Lecturer, 化学系, 講師 (10251034)
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| Research Abstract |
In the present study, we intend to show experimentally kink-type solitons formed by the displacements of hydrogen positions in crystal, which has been theoretically studied for a long time as an interesting mechanism for the energy transfer in a long-range in solids and biological systems, but few experimental data were given. For this purpose, we applied nuclear quadrupole resonance(NQR) technique which enables subtle changes of electric charge displacements in crystals.
1) We constructed a liquid He cryostat and attached it to our NQR spectrometer which could be used down to liquid nitrogen temperature to extend the temperature range down to 4.2 K.
2) Using this spectrometer, we measured NQR frequencies and its spin-lattice relaxation time in p-chlorobenzoic acid which has shown to from a hydrogen-bonded dimer structure and the proton exchange in crystal. In this system, we could detect the effect of proton transfer at the Cl position even far from protonic positions, and show a high sensitivity of NQR which can observe the fluctuation of the electric field gradient made by remote proton exchanges via conjugated systems.
3) We extended this work to hydrogen network systems with more hydrogens, i.e., chloranilic acid-1,4 and -1,2 diazine(1 : 2) hydrogen-bonded molecular complexes consisting of three molecular units. We could observe three kinds of protonic transfers in this unit, although only a single motion was observed by proton NMR study.
In these studies, we could detect by the NQR method, for the first time, the proton transfer in hydrogen-bonded system, and showed that NQR is a quite sensitive technique for hydrogen transfer mechanism in solid.
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