Ratiometric detection of Raman hydration shell spectra

The micro‐structure of hydration shell of solute in water is significant for understanding the properties of aqueous solutions. However the spectra of hydration shell are difficult to be obtained. Herein, a novel Raman ratio spectra, which is obtained through dividing the Raman spectra of aqueous solutions from the spectrum of water, was applied to deduce the spectra of hydration shell of organic (acetone‐D6) and inorganic compounds (NaNO₃, NaSCN, NaClO₄, Na₂SO₄, NaCl) in water. Those spectra of the hydration shell were employed to study the micro‐structures of the first hydration shells of anions, the number of water molecules in the first hydration shell of free anions and acetone‐D6, and the aggregation behavior of ions in the concentrated aqueous NaNO₃. The number of water molecules in the hydration shell was supported by our molecular dynamic simulations. The Raman ratio spectra can be widely employed to obtain the spectra of the first hydration shell, and it is helpful to understand the micro‐structure of aqueous solutions. Copyright © 2016 John Wiley & Sons, Ltd.     

飞秒激光参数对三态阶跃型分子Autler-Townes分裂的影响

利用三态模型和含时波包法, 研究了K₂分子在强飞秒泵浦-探测激光场中泵浦/探测场强、波长对光电子能谱Autler-Townes(AT)分裂的影响．通过分别改变两激光场的场强或者波长预测AT峰移和间距,并且首次量化了AT分裂的峰移和间距．光电子能谱在共振时显示为对称双峰,失谐时为非对称双峰。AT分裂间距随泵浦场强增大而增大,但不因探测场强改变而改变．     

通过双Σ型激光方案控制振动态布居转移

通过使用含时量子波包方法,对HF分子该类型的布居转移动力学进行了研究. 提出双Σ型激光控制方案,用于控制布居从|v=16>能级向|v=0>能级进行转移. 该方案的第一步是将布居从|v=16>经过中间能级|v=11>向|v=7>转移,第二步是将布居从|v=7>经过中间能级|v=3>向|v=0>转移. 在每一个步骤中,三个振动能级在两束重叠的激光脉冲作用下形成一个Σ型的布居转移路径. 通过优化激光的强度、频率和延迟时间,得到了最大的布居转移效率. 计算并比较了正序脉冲和反序脉冲两种情况,在这两种情况下,布居都可以超过90%从|v=16>能级向|v=0>能级进行转移.     

Energy structure and absorption spectra of colloidal CdS nanocrystals in gelatin matrix

We investigate the energy structure of colloidal CdS nanocrystals by measuring the UV–vis absorption spectra. Nanocrystals were synthesized by sol–gel method in a gelatin matrix in the size range from 2.5 to 3.9 (±0.2) nm. In order to interpret the UV–vis absorption spectra we calculate the energy spectrum of electron quasi-stationary states using the model of open nanocrystal as well as the hole stationary spectrum in a two-band approach. It is shown that the main contribution to the absorption spectrum is made by interband transitions 1S_3/2→1S_e and 1P_3/2→1P_e, and its shape is determined by the size distribution of nanoparticles. For this system the estimated values of the effective masses of the heavy hole and light hole are 1.44m₀ and 0.28m₀, respectively.     

新型鸟嘌呤类似物y-鸟嘌呤及其异构体电子光谱性质的理论研究

荧光核酸碱基类似物的设计合成是众多研究领域的热点课题. 本文利用密度泛函理论(DFT)和含时密度泛函理论(TDDFT)考察了新型鸟嘌呤类似物y-鸟嘌呤(yG-t1) 及其五个异构体(yG-t2到yG-t6)的结构性质、电子性质和光谱性质, 同时考察了甲醇溶剂和碱基配对对其光谱性质的影响. 研究表明, 气相中y-鸟嘌呤的标准结构并不是最稳定的结构, 其具有三个能量相近的异构体, y-鸟嘌呤最有可能以这三种形式存在. 光谱性质研究表明y-鸟嘌呤的最大吸收波长比天然鸟嘌呤大得多, 人们可以对其进行选择性激发. y- 鸟嘌呤的标准结构与其异构体显示出不同的光谱特性, 因此可以利用其电子光谱指纹对它们进行区分. 研究发现甲醇溶剂将使y-鸟嘌呤标准结构的最大吸收波长和荧光发生蓝移, 而使其他异构体相应值发生红移; 与胞嘧啶配对将使yG-t1, yG-t2, yG-t5 和yG-t6的最大吸收波长和荧光波长发生蓝移, 表明y-鸟嘌呤的电子光谱性质受环境影响较大.     

Fenna-Matthews-Olson捕光复合物中的冗余结构

研究了绿色硫细菌中捕光天线复合物Fenna-Matthews-Olson的一个子单元和反应中心的能量传递.通过细菌叶绿素分子的能量和耦合强度,构建了包含反应中心的哈密顿量及约化模型.通过级联运动方程研究了不同分子间和反应中心的激子布居演化.计算了Fenna-Matthews-Olson及其约化模型的二维三阶光子回波谱,获得能量传榆过程中不同激子态间的相干性.结果表明在能量捕获过程中,Fenna-Matthews-Olson复合物存在冗余结构.     

Synthesis,spatial structure and spectral properties of pyrylo‐4 (thio) squaraines variously substituted in cyclobutene moiety

Synthetic routes have been developed to a number of (thio) squaraine dyes containing the residues of CH‐acids at the central cyclobutene ring. The electronic and spatial structure as well as the chemical conversions and optical behaviour of the compounds obtained have been studied both theoretically and by X‐ray diffraction analysis, ¹H NMR and electronic spectroscopy. As shown, the electronic nature and sterical characteristics of the central ring substituents give rise to some general conformational features and crystal packing regularities and also govern the spectral position of the first π–π^* absorption band. The structure–property relationships established in the study provide guidance for the purposeful design of deeply coloured (thio) squaraines. Copyright © 2015 John Wiley & Sons, Ltd.     

几种外场对费米共振的影响:费米共振的拉曼光谱研究

费米共振是分子内和分子间发生的基团间的振动耦合和能量转移现象。有关外场中费米共振的认识、拉曼光谱的研究方法及应用均待开发和推广。本文系统阐述了利用高压DAC技术、变温技术特别是课题组独创的变换溶剂浓度、LCOF等方法获得的有关费米共振的研究成果,即分子场、压力场、温度场等外场对分子内和分子间费米共振的影响:(1)分子场中a.由C_5H_5N在CH_3OH和H_2O中拉曼光谱变化研究表明溶剂效应对费米共振有明显影响;b.通过改变溶液浓度发现了其他方法未能发现的费米共振双线对非对称移动及双线对中倍频的基频亦受费米共振调谐的现象;c.溶液中的氢键、反氢键使分子基团重组而对费米共振产生显著影响;d.C_7H_8和m-C_8H_(105分子间发生会费米共振,且费米共振特性随溶液浓度明显改变;(2)压力场中a.随压强增加谱线蓝移,且频差△随压强改变而引起W改变;b.随压强增加CCl_4在C_6H_6中的v_1+v_4~v_3的W减小速度比纯液体中快,费米共振消失提前。这表明,压强引起的费米共振现象可揭示溶剂效应机理;(3)温度场中温度会影响分子费米共振特性,且对不同分子影响亦不同,温度对CO_2的费米共振影响较大,而对CS_2几乎无影响。本文对分子谱线的认证与归属、分子构象的确定及异构体的鉴别、氢键对分子结构与性质的影响等方面的研究提供了系统的理论与实验依据。     

Doppler程序对金红石型TiO2的空位缺陷研究

金红石型TiO2是一种非常好的稀磁半导体材料,其自身的本征缺陷与室温铁磁性起源密切相关。本文利用Doppler程序在广义梯度理论（GGA）的基础上,计算了正电子在金红石型TiO2块材中不同缺陷处的湮没寿命。主要包括自由态正电子的湮没寿命,单空位和双空位处束缚态正电子的湮没寿命。并从理论上给出了含有空位缺陷时金红石型TiO2的符合多普勒展宽能谱。