手性分子反-2,3-环氧丁烷的旋光拉曼光谱研究

本文从拉曼峰强出发,求得了反-2,3-环氧丁烷分子的拉曼键极化率,明确了拉曼激发下电荷的分布的信息.还从旋光拉曼(Raman optical activity,ROA)谱的峰强,求取了该分子的旋光拉曼键极化率.由分子手性中心的C-H产生的偶极矩与拉曼激发过程中,电荷流动产生的跃迁磁偶极矩的耦合,来理解旋光拉曼活性产生的机理.分析表明,旋光拉曼活性分子手性中心的C-H键两侧的旋光拉曼极化率符号相反,显示着手性分子局域的不对称性.还得到了对称和反对称坐标的键极化率和旋光拉曼极化率,并且从对称性的角度,即C2群的不可约表示,讨论了这些极化率的内涵.     

Orbital Valence,Urey-Bradley and Approximate General Valence Force Fields and Vibrational Mean Amplitudes of Some Spherical Top M(CH3)4 Type Molecular Model (M=C,Si, Ge,Sn and Pb)

The intramolecular force fields of tetramethylcarbon, tetramethylsilane, tetramethylgermanium, tetramethyltin and tetramethyllead have been examined using OVFF, UBFF and GVFf potential functions under the approximation of ‘point-mass’ for methyl group. Approximate force fields for the (2x2)F₂ species of each molecule have been examined using L₁₂=O, L₂₁=O and P.E.D., methods. Transferability of OVFF into GVFF has also been observed. An analysis of the Coriolis coupling constants has been presented in the light of the force fields of the molecules. Vibrational mean amplitudes for bonded and non-bonded distances have been reported and analysed. The Bastiansen-Morino shrinkage effedt has been evaluated. The results have been discussed in the light of the relative behaviour of the molecules.     

GaAs中碳受主局域振动模的非简谐性对主吸收带的影响

在ＧａＡｓ中碳受主局域振动模主吸收带低能侧,观察到一个吸收边带,其峰频率与局域振动模吸收主带的峰频率之差为３５ｃｍ＾－１。该边带的积分面积随温度变化,并影响主吸收带积分布积的温度关系。该边带可能起因于局域振动模自身的非简谐性。     

Effect of Guided Acoustic Wave Brillouin Scattering on Pulsed Squeezing in Optical Fibers with Nonlinearity and Dispersion

Quadrature squeezed light generation with optical pulses in a fiber loop mirror is analyzed through computer simulation. The effect of guided acoustic wave Brillouin scattering (GAWBS) in optical fibers as well as those of nonlinearities and chromatic dispersions are considered for the first time. The relation between the GAWBS noise and the optical pulse width is discussed in detail. It is found that the nearly fundamental soliton pulse is optimum to get the largest squeezing even if the GAWBS noise is effective. The broadened pulses suffer larger degradation of squeezing due to this noise.     

Effect of glutaphen on generation of active oxygen species, photosynthetic electron transport, and the functional activity of photosystem 2 in Chlorella cells

Treatment of chlorella green algae (Chlorella sp.) for 2 h in the dark with the photodynamic herbicide glutaphen (GTP), consisting of 0.3 mM 1,10-phenanthroline and 0.6 mM glutamic acid, followed by illumination leads to efficient generation of active oxygen species (AOS). After 15 min of illumination, AOS accumulation reaches 200% compared with the level in cells of the control culture, then it decreases down to 130% and 115% after 1 day and 3 days of illumination. During the first few days after treatment, we observe inhibition of synthesis of a specific precursor of chlorophyll (Chl): 5-aminolevulinic acid molecules, and then we observe stimulation of the synthesis. The effect of GTP on the photosynthetic activity of chlorella does not depend on the AOS level but rather remains uniform, in contrast to its effect on the Chl biosynthesis system. GTP does not change the efficiency of light harvesting and charge separation at the reaction centers of photosystem (PS) 2, but significantly lowers the functional efficiency of the electron transport chain: the photochemical quenching constants for Chl a fluorescence and the effective quantum yield of photochemical reactions in photosystem 2 decrease. The major mechanism of action for GTP is probably displacement of the secondary quinone acceptor Q_B from its binding site on the D1 protein by the 1,10-phenanthroline, consequent inhibition of electron efflux from Q _A ⁻ and increase in the fraction of Q_B-nonreducing centers of PS 2. The active oxygen species generated in the cells have a photodegradative effect on the Chl biosynthesis system, in particular on its initial steps, and do not involve already formed pigment-protein complexes of PS 2. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 801–806, November–December, 2006.