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Shiga, Motoyuki
no journal, ,
In recent years, the use of high-temperature water as a reaction field is being actively discussed in the field of green chemistry. A novel approach from theoretical and computational chemistry is expected to play the important part in its basic understanding, e.g. how the water molecules are involved in the reactions. For this aim we study herein one of the prototypical reactions, 2,5-hexanediol dehydration, which is known as a promising way for the conversion of biomass-derived polyalcohols using the high temperature carbonated water. To clarify the whole reaction mechanism we carried out three different ab initio simulations; we used string method to extract the reaction coordinate, metadynamics to calculate the free energy landscape, and molecular dynamics to explore the trajectory in real time.
Yokoyama, Keiichi; Kobayashi, Takanori*
no journal, ,
We report a consideration on the non-linear optical response of molecules rotationally excited by impulsive Raman scattering. An ensemble of molecules which are cascadedly excited and de-excited among the rotational levels by a several numbers of Raman transitions is not uniform in spatial coherence and depend on the number of transition the molecule undergoes. Therefore, there is a possibility to obtain signal waveforms which cannot be explained by the conventional analysis method which ignores the non-locality of the density operator. In this study, we adopted non-local density operator to calculate non-linear optical response in such case. As a result, we predicted that significant angular dependence of observed signal appear due to the spherical wave of input pump laser pulse. We qualitatively confirmed the analysis reproduce the observed waveform.
Saeki, Morihisa*; Matsumura, Daiju; Taguchi, Tomitsugu*; Yomogida, Takumi; Oba, Hironori*
no journal, ,
We are developing wet separation of precious metals using photo-induced particle formation. Previously we demonstrated that this method could effectively separate a palladium (Pd) metal from a mixed solution with a molybdenum (Mo) ion. In this work, we showed that the Mo ion plays a role as a photosensitizer in the photo-induced particle formation of Pd in an acidic condition by time-resolved X-ray fine structure (XAFS) measurement.