Molecular dynamics study of the spectroscopic properties of liquid benzene

A molecular dynamics (MD) simulation, which includes all degrees of freedom of atomic motion, has been performed to investigate several spectroscopic properties such as infrared and Raman spectra, permittivity, and refractive index of liquid benzene. Infrared and Raman spectra of liquid benzene were measured at room temperature, and these experimental results were compared with our MD simulated spectra. The simulated infrared spectra reproduced the four fundamental v ₁₁, v ₁₈, v ₁₉, and v ₂₀ bands, and the simulated Raman spectra reproduced the seven fundamental v ₁, v ₂, v ₆, v ₇ v ₈, v ₉, and v ₁₀ bands as expected from the selection rule. These simulated spectra were in good agreement with the observed ones in the frequency and relative intensity of fundamental vibrations of benzene. The v ₁₆ and v ₄ bands appeared in the simulated Raman spectra. These bands are exceptions to the selection rule, and these facts indicate that the breakdown of the symmetry of D_6h of a benzene molecule occurs in a liquid state. The simulated permittivity, and refractive index were also in good agreement with other experimental values.     

Chain length dependence of high magnetic field effects on lifetimes of radical ion pairs linked by a methylene chain: interpretation by both spin—lattice and spin—spin relaxations

High magnetic field dependence of lifetimes of methylene-chain-linked radical ion pairs (RIPs) generated by photo-induced electron transfer from zinc(II) porphyrin to viologen has been confirmed in aqueous acetonitrile using a pulse magnet-laser flash photolysis apparatus. In the case of a short methylene chain it was first revealed that the dependence was definitely different from that for a long one, and was characterized by a reversal in the dependence. In addition to a long lifetime independent of the magnetic field, RIP in fields above 7T exhibited short lifetimes that depended on the field. These results were interpreted not only by spin-lattice (longitudinal) relaxation but also by spin-spin (transverse) relaxation in RIPs.     

Theoretical study on lower electronic states of the FeSi molecule

The low lying electronic states of the FeSi molecule have been investigated by performing complete active space self-consistent field (CASSCF) and multireference single and double excitation configuration interaction (MRSDCI) calculations. Although the classification of the ground state was not established, the results of the MRSDCI calculations suggest that the ground state of FeSi is ³Δ, and the lowest excited state is ⁵Π whose transition energy is 0.36 eV including the Davidson-type Q correction. The R _e given by MRSDCI with Q correction is 2.23 Å for ³Δ and 2.19 Å for ⁵Π. The spectroscopic constants and dipole moments of the low lying ⁵Δ and ³Π states as well as the ³Δ and ⁵Π states are also evaluated. The bonding nature of FeSi in the ³Δ state is discussed in comparison with the FeC molecule.     

基于莫尔信号的精密位移测量与控制的研究

应用光衍射理论分析了一种纳米级位移分辨率的双级衍射光栅测量系统,建立了衍射莫尔信号与对应位移的数学模型,并通过计算机仿真对莫尔信号的位移特性进行了研究。在此基础上构建了一套精密位移测量与控制装置,取差动零次激光莫尔信号为控制信号,由微机控制实现高精度位移检测及全自动精密定位。实验结果表明,基于激光莫尔信号的精密检测与控制装置可获得得5nm的位移分辨率及±0.4μm的定位精度。