Dynamics of Moiecular Glasses Studied by Using Partially Deuterated Systems

我们已经measured the inelastic neutron scattering (INS) of the glasses of some deuterated alcoholsto investigate the microscopic mechanism of the boson peak. the measured samples are glassypropanols and glycerols selectively deuterated at hydroxyl and/or alkyl groups. The observed INSspectra are dominated by the vibrations of the parts with hydrogen atoms since incoherent scatteringcross section of hydrogen atom is more than 10 times larger than those of other atoms. We usedAGNES spectrometer belonging to Institute of Solid State Physicsthe University of Tokyo. A boson peak appeared at around 2 meV in propanols and 3.5 meV inglycerols. The peak energy and intensity were not改变much by The deuterations for bothalcohols This indicates that the origin of the boson peak is the cooperative vibration of thehydrogen bond network (or chain) and alkyl parts. The present results qualitatively agreed with Thebroken network model recently developed by Nakayama.We have performed the INS experiment of theglasses of potassium metaphospate deuterate (KPO D23 D22 D22 D2O). by using MARIspectrometer in Rutherford Appleton实验室UK. The coherent INS spectrum showed that The boson observed at 3-4 meV in The incoherent spectrumis split into two peaks at 2.5 and 6 meV. This is a new finding很可能与一个人相关dimensional network of the present material.我们也曾发现过dispersive nature of theacoustic phonon in the scattering intensity map in the momentum vs energy transfer plane. theperiodicity of the dispersion corresponded to that of static structure factor S (Q). This phenomenon可能与网络玻璃的良好定义local结构相关。

We have measured the inelastic neutron scattering (INS) of the glasses of some deuterated alcohols to investigate the microscopic mechanism of the boson peak. The measured samples are glassy propanols and glycerols selectively deuterated at hydroxyl and/or alkyl groups. The observed INS spectra are dominated by the vibrations of the parts with hydrogen atoms since incoherent scattering cross section of hydrogen atom is more than 10 times larger than those of other atoms. We used AGNES spectrometer belonging to Institute of Solid State Physics, the University of Tokyo. A boson peak appeared at around 2 meV in propanols and 3.5 meV in glycerols. The peak energy and intensity were not changed much by the deuterations for both alcohols. This indicates that the origin of the boson peak is the cooperative vibration of the hydrogen bond network (or chain) and alkyl parts. The present results qualitatively agreed with the broken network model recently developed by Nakayama.We have also performed the INS experiment of the glasses of potassium metaphospate deuterate (KPOィイD23ィエD2・0.70DィイD22ィエD2O). by using MARI spectrometer in Rutherford Appleton Laboratory, UK. The coherent INS spectrum showed that the boson observed at 3-4 meV in the incoherent spectrum is split into two peaks at 2.5 and 6 meV. This is a new finding probably related to the one dimensional network of the present material. We have also found the dispersive nature of the acoustic phonon in the scattering intensity map in the momentum vs energy transfer plane. The periodicity of the dispersion corresponded to that of static structure factor S (Q). This phenomenon may be related to the well-defined local structure of the network glass.