I2-环己烯复合物的共振拉曼光谱和密度泛函理论计算研究

实验得到I2-环己烯电荷转移复合物的电子吸收光谱和共振拉曼光谱.用密度泛函方法计算了复合物的基态结构、振动频率和电子跃迁能.计算和吸收光谱实验结果表明,I2-烯烃复合物在约300nm处的强吸收带为pz(I17)→π*(C=C)跃迁,即由靠近C=C双键端的碘原子(I17)上的一个pz电子向C=C双键反键轨道跃迁引起的吸收.在约300nm共振拉曼光谱的强度模式表现为I—I伸缩振动模和C=C伸缩振动模的基频、泛频及其组合频,表明在该激发态上I2-环己烯复合物经历了显著的I—I和C=C的价键变化.     

4'''',5,7-三羟基二氢黄酮与人血清白蛋白相互作用的光谱学研究

应用紫外吸收光谱、荧光光谱和红外光谱等方法对人血清白蛋白(HSA)与4',5,7-三羟基二氢黄酮(naringenin,NAR)相互作用的机理进行了研究.紫外光谱显示,在生理pH下NAR分子中A环7位的酚羟基发生部分解离,7位酚羟基的解离使A环与B环上羰基形成的共轭体系的紫外吸收峰发生明显红移;药物与蛋白质的相互作用使该谱带发生了进一步的红移,说明该共轭体系参与了与蛋白质的相互作用.在药物与蛋白质浓度比(cNAR/cHSA)为0.1～10的范围内,NAR在HSA上只有一个结合位点(可能位于site I),结合常数为1.27×105L·mol~(-1)(n=5,RSD小于5%).研究了不同pH值条件下药物对蛋白质荧光猝灭的影响,发现药物分子中的没有解离的活性基团在结合过程中发挥着主导作用.在缓冲水溶液和重水溶液中分别测定了与药物作用前后蛋白质二级结构的变化.随着药物浓度的增加,NAR和HSA之间的相互作用使HSA的α-螺旋结构的含量明显降低,而β-折叠和β-转角结构的含量增加,无轨结构在药物浓度较高时也有少量的增加.结合紫外吸收光谱、荧光光谱和红外光谱结果,探讨了HSA与NAR相互作用的模式.     

荧光法研究牛血清白蛋白与中性红的相互作用

用荧光光谱、同步荧光光谱、三维荧光光谱和吸收光谱研究了牛血清白蛋白与中性红的结合反应特征,用Stern-Volmer方程和Lineweaver-Burk双倒数函数方程等处理实验数据,得到了15℃时动态猝灭常数kq=5.434×1012L.mol-1.s-1;静态猝灭结合常数KLB=3.300×104L.mol-1,结合位点数n=1.18,根据F ster能量转移原理计算出中性红在牛血清白蛋白上的结合距离r=2.63 nm。     

纳米金三明治结构调制细胞色素c电子传递特性的分子机理研究

以细胞色素c(Cyt c)为模型蛋白,采用表面增强红外吸收光谱监测了三明治结构所吸附的纳米金对氧化还原诱导的Cyt c表面增强红外差谱的改变.研究表明,在单层Cyt c分子表面组装纳米金,使得血红素的红外差谱特征峰明显增强,这归因于纳米金和血红素之间的电子传递.纳米金与Cyt c氧化还原活性中心血红素的相互作用加速了蛋白质的电子传递.这为实现并优化表面吸附蛋白质的直接电化学提供了一种新技术.     

HEK-TCNQ的光诱导电荷转移与HEK-DDQ的基态电荷转移

合成了电荷转移复合物HEK-TCNQ和HEK-DDQ(HEK=9-hydroxyethylcarbazole)。拉曼光谱和吸收光谱测定表明: 光电导为10^-^1^1s.cm^-^1的HEK-TCNQ在514.5nm激光照射下可发生电荷转移, 生成HEK^+TCNQ^-, 其光电导显著增大。X射线结构分析和红外光谱表明: HEK与DDQ之间基态电荷转移量为0.1~0.2。     

新型高分辨宽带和频振动光谱仪在中科院面世

<正>高分辨宽带和频振动光谱(high-resolution broadband sum frequency generation vibrational spectroscopy,HR-BB-SFG-VS)是研究界面分子间相互作用的前沿光谱技术。最近,中科院化学所分子反应动力学国家重点实验室在国家自然科学基金委重大仪器研制项目的支持下,成功研制了具有亚波数分辨(1 cm~(–1))的界面和频振动光谱系统。本仪器最终测试指标达到或优于最初的设计参数。其飞秒红外脉冲的半高宽大于250波数,可一次性覆盖400波     

江苏盱眙出土夹纻胎漆器的测试分析

采用激光拉曼光谱、X射线荧光光谱、红外吸收光谱等方法对盱眙出土的夹纻胎漆器进行了分析研究.研究发现漆膜中的红色颜料和暗黑色颜料分别是HgS和CuS;漆灰的填料以粘土类物质为主,存在着加入骨灰的工艺;生漆被使用在漆灰制作、色漆调制等方面,起到了成膜剂的作用;麻胎之间采用漆灰作为胶合剂.     

钢铁研究总院、中国科学院物理研究所、北京大学、清华大学联合承办的《光谱学与光谱分析》2003年征订启事

《光谱学与光谱分析》1 984年创刊 ,国内统一刊号ＣＮ1 1 - 2 2 0 0 /Ｏ4,国际标准刊号 :ＩＳＳＮ 1 0 0 0 0 5 93国内外公开发行 ,大 1 6开 ,1 76页 ,双月刊 ;中国科协主管 ,钢铁研究总院、中国科学院物理研究所、北京大学、清华大学共同承办的学术性刊物。北京大学出版社出版 ,每期售价 2 3 0元 ,全年 1 3 8元 ;国内邮发代码82 6 8,国外发行代码ＢＭ90 5。刊登主要内容 :激光光谱测量、红外、拉曼、紫外、可见光谱、发射光谱、吸收光谱、Ｘ射线荧光光谱、激光显微光谱、光谱化学分析、国内外光谱化学分析领域内的最新研究成果、开创性…     

《光谱学与光谱分析》2004年征订启事

《光谱学与光谱分析》1 981年创刊 ,国内统一刊号CN 1 1 - 2 2 0 0 O4,国际标准刊号 :ISSN 1 0 0 0 -0 5 93 ,国内外公开发行 ,大 1 6开 ,1 2 8页 ,月刊 ;是中国科协主管 ,钢铁研究总院、中国科学院物理研究所、北京大学、清华大学共同承办的学术性刊物。北京大学出版社出版 ,每期售价 1 8.0元 ,全年 2 1 6元 ;国内邮发代码 82 - 6 8,国外发行代码M90 5。刊登主要内容 :激光光谱测量、红外、拉曼、紫外、可见光谱、发射光谱、吸收光谱、X -射线荧光光谱、激光显微光谱、光谱化学分析等领域内的最新研究成果、开创性研究论文、学科发展…     

多司马酯的波谱特征与结构确证

对多司马酯的紫外(UV)光谱、红外(IR)光谱、氢谱(^1HNMR)、碳谱(^13CNMR)、氢氢相关谱(^1H-^1HCOSY)、碳氢相关谱(HETCOR)及碳氢远程相关谱(COLOC)进行了解析报道,并对所有的^1HNMR,^13CNMR谱的信号进行了归属,讨论了红外吸收光谱峰所对应的官能团的振动形式。     

Apparatus for High-Resolution Solid Hydrogen Matrix Isolation Spectroscopy and Its Application

Apparatus integrating a Fourier transform-infrared (FT-IR) spectrometer and a mid-infrared difference frequency generation (DFG) laser spectrometer was built for the study of the matrix isolation spectrum in solid molecular hydrogen. A 3-cm-long molecular hydrogen crystal was grown in a liquid-helium Dewar, and its infrared absorption spectrum in the 1-5 μm region was recorded to test the system. The W₀(0) (ν=0←0, J=6←0) line around 2410 cm⁻¹ of solid hydrogen was investigated with the DFG laser spectroscopy. High-resolution matrix isolation spectrum of CO² co-deposited with hydrogen on a BaF₂ cold plate at liquid-helium temperature was studied.     

溶剂热合成纳米球状La2O2S:Eu3+荧光粉

Eu3+离子激活的硫氧化物荧光粉是目前国内外广泛使用的CRT红色发光材料[1]. 它具有色纯度高、色彩不失真、亮度-电流饱和度特性好和稳定性高等特性, 已成为CRT不可替代的红色荧光粉. 此外, 掺杂或不掺杂Eu3+的硫氧化镧是还原SO2有害气体为S单质的优良催化剂[2,3]. 近年来兴起的纳米材料是有可能在本世纪得到广泛应用的材料; 掺杂稀土离子的硫氧化物有望应用于各种显示技术及催化剂中. 最近, 吴长峰等[4]在Y2O3∶Eu3+纳米管中观察到发射峰展宽等特性. 因而, 研究Eu3+离子激活的硫氧化镧纳米荧光粉是很有意义的.     

气相CBr2的激光诱导荧光光谱

本文报道了在交叉分子束装置中氟原子和二溴甲烷反应生成的CBr2的气相激光诱导荧光光谱的首次实验结果。位于585-664nm范围内的激光诱导荧光光谱由22个峰组成,被指定为CBr2的A(V1'V2'0)←X(000)(V1'=0,1; V2'=0-12)跃迁。从光谱导出v00=14885cm^-^1, 上态振动光谱常数v1'=460, v2'=189cm^-^1, x12'=3.10,x22'=-0.27cm^-^1。本实验结果与CBr2的低温固相光谱进行比较, 发现固相光谱较气相光谱明显蓝移, 确认了CBr2是F+CH2Br2过程的两步反应的产物。     

样品化学环境对激光质谱的影响

本文从三个方面研究了样品化学环境对激光解吸质谱行为的影响，利用ＮＣ膜对水溶液的吸附作用并以此为基底，研究了水溶液中中性分子Ｎ，Ｎ，Ｎ’，Ｎ’－四甲基－１，４苯二胺（ＴＭＰＤ）（电子供体）与苯醌（ＢＱ）（电子受体）之间的电荷转移对质谱图分子离子峰强度的影响；并用此法对４－氨基－ｎ－丁酸和２－萘酚的ＰＫ值进行测定；同时也研究了镁、铜和钴四苯基卟啉化合物在弱酸性的固相基体中激光质谱行为。研究结果说明了化学环境对激光质谱行为的密切关联。     

Source of slow lithium atoms from Ne or H2 matrix isolation sublimation

We have studied, via laser absorption spectroscopy, the velocity distribution of (7)Li atoms released from cryogenic matrices of solid neon or molecular hydrogen. The Li atoms are implanted into the Ne or H(2) matrices--grown onto a sapphire substrate--by laser ablation of a solid Li or LiH precursor. A heat pulse is then applied to the sapphire substrate sublimating the matrix together with the isolated atoms. With a NiCr film resistor deposited directly onto the sapphire substrate we are able to transfer high instantaneous power to the matrix, thus reaching a fast sublimation regime. In this regime the Li atoms can get entrained in the released matrix gas, and we were also able to achieve matrix sublimation times down to 10 μs for both H(2) or Ne matrix, enabling us to proceed with the trapping of the species of our interest such as atomic hydrogen, lithium, and molecules. The sublimation of the H(2) matrix, with its large center-of-mass velocity, provides evidence for a new regime of one-dimensional thermalization. The laser ablated Li seems to penetrate the H(2) matrix deeper than it does in Ne.     

Infrared spectroscopic and density functional theory study on the reactions of rhodium and cobalt atoms with carbon dioxide in rare-gas matrixes

Reactions of laser-ablated rhodium and cobalt atoms with carbon dioxide molecules in solid argon and neon have been investigated using matrix isolation infrared spectroscopy. The OMCO, O2MCO, OMCO(-) (M = Rh, Co), OCo2CO, and OCoCO(+) molecules have been formed and characterized on the basis of isotopic shifts, mixed isotopic splitting patterns, ultraviolet irradiation, CCl4-doping experiments, and the change of laser power. Density functional theory calculations have been performed on these products. The overall agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts supports the identification of these products from the matrix infrared spectrum.     

Infrared spectra and theoretical calculations of KH and (KH)2 in solid hydrogen

A matrix isolation IR study of laser-ablated potassium atom reactions with H2 has been performed in solid molecular hydrogen. The KH molecule and (KH)2 cluster were identified by infrared spectra with isotopic substitution (HD and D2) and by comparison to frequencies calculated using density functional theory. In para-hydrogen, the sharp KH absorption suggests dihydrogen complex formation with the ionic KH molecule, which is also characterized by an absorption at 4095 cm(-1). The highly ionic rhombic (KH)2 molecule is formed by dimerization and trapped in solid hydrogen. Calculations at the CCSD(T) level of theory show the increasing ionic character and decreasing stability for the (MH)2 molecule series from Li to Cs.     

Can stimulated Raman pumping cause large population transfers in isolated molecules?

When stimulated Raman pumping (SRP) is applied to a stream of isolated molecules, such as found in a supersonic molecular beam expansion, we show that SRP can neither saturate nor power broaden a molecular transition connecting two metastable levels that is resonant with the energy difference between the pump and Stokes laser pulses. Using the optical Bloch-Feynman equations, we discuss the pumping of the hydrogen molecule from H(2) (v = 0, J = 0, M = 0) to H(2) (v = 1, J = 2, M = 0) as an illustration of how coherent population return severely reduces the SRP pumping efficiency unless the pump and Stokes laser pulses are applied with an appropriate relative delay and ratio of intensities.     

温控分子动力学研究微管蛋白活性肽链的折叠机制

运用温控和常温分子动力学方法, 研究了微管蛋白活性部位Pep1-28肽链的折叠机制, 总模拟时间为380.0 ns. 对于温控分子动力学, 逐渐降温可以清晰显示Pep1-28肽链的折叠途径, 发生明显折叠的温度约为550 K, 其折叠和去折叠可逆机制为U(>1200 K)←→I1(1200-1000 K)←→I2(800 K)←→I3(600 K)←→I4(450 K)←→F1(400 K)←→F2(300 K), 其中U为去折叠态构象, I1、I2、I3和I4是折叠过程中的四个重要的中间态构象, F1和F2是两个结构相近的折叠态构象. 对于常温(300 K)分子动力学, 其构象转变和折叠过程相当迅速, 很难观察到有效、稳定的中间态构象. 尤其引人注意的是, 其折叠态结构陷入了能量局域极小点, 与温控(300 K)的有较大差异, 两者能量差高达297.53 kJ·mol-1. 可见, 温控分子动力学方法不仅清晰地显示多肽和蛋白质折叠过程的重要中间态构象, 为折叠和去折叠机制提供直接、可靠的依据, 而且还有助于跨越较高的构象能垒, 促使多肽和蛋白质折叠以形成全局能量最低的稳定结构.     

Microwave spectrum of bicyclo[2,2,1] hepta-2,5-dien-7-ol and spectroscopic evidence for an intramolecular (OH π) hydrogen bond

The microwave spectrum of bicyclo[2,2,1]hepta-2,5-dien-7-ol and of the deuteroxyl species have been recorded over 8–40 GHz. Rotational constants and centrifugal distortion constants were fitted to the measured rotational transitions for both species. The electric dipole components μm_a = 1.223(3) D, μm_b = 1.053(2) D and μm_total = 1.614(2) D were deduced from Stark splittings. Only a trans conformation of the OH group with respect to the hydrogen is compatible with the microwave data.Infrared spectra of bicyclo[2,2,1]hepta-2,5-dien-7-ol and the corresponding saturated compound have been recorded in the gas phase and in Ar matrix isolation. The difference of 77.4 cm⁻¹ in the O---H stretching frequencies between unsaturated and saturated compounds points towards a moderately strong intramolecular (OH π) hydrogen bond.