甲醇和乙醇的三维荧光光谱特性研究

为阐明甲醇和乙醇的光谱学特性,建立两者快速的辨析方法。采用三维荧光光谱,对甲醇和乙醇的荧光特性进行了研究。分析结果显示,甲醇的三维荧光光谱中出现了两个特征荧光峰,其荧光强度在甲醇体积浓度小于15%时与其浓度成正相关,乙醇的三维荧光光谱中出现了一个完整的特征荧光峰,其荧光强度在乙醇体积分数小于50%时与乙醇浓度成相关,甲醇比乙醇具有更高的荧光效率,以甲醇为有机溶剂研究化合物的荧光特性时,需要考虑甲醇的本底荧光。甲醇和乙醇的特征荧光峰位置差别较大,前者特征荧光峰出现在225/35 0nm和250/375nm处,而后者特征荧光峰位于240/310nm,据此可以有效辨析两种醇。     

甲醇荧光光谱的量子分析

通过量子近似计算研究了甲醇的荧光光谱.将甲醇分子近似看成双原子分子,甲基和羟基分别为原子实,氧原子未共享电子对看成价电子.利用数值计算的方法对双原子分子电子能级差进行估算,得到电子能级差为一个仅与分子线度相关的函数.然后把C-O键长作为分子线度代入前面得到的函数中,算出甲醇分子主跃迁能级差,并将所得结果与实验值进行对比,误差仅为2.2%,理论计算与实验结果吻合.     

西维因在甲醇-水二元混合溶剂中的三维荧光光谱特性研究

农药的广泛使用对环境产生了重要的影响,西维因作为一种重要的广谱高效杀虫剂在很多地表水中残留,了解和掌握西维因在环境中的光谱特性及检测方法具有重要意义。研究了西维因的激发-发射三维荧光光谱特性,通过改变甲醇-水二元混合溶剂中甲醇的体积比,探讨了不同体积比的甲醇-水混合溶剂对西维因三维荧光光谱的影响。研究结果表明,西维因的特征荧光光谱峰为单峰,西维因的激发波长和发射波长范围分别处于： 244~304和300~350 nm,最大激发/发射峰位置分别位于280和335 nm。随着甲醇-水二元混合溶剂中甲醇含量的增加,西维因的三维荧光光谱未出现明显位移,但是荧光光谱强度随甲醇含量的增加出现了非线性的变化,这主要与二元混合溶剂自身独特的性质有关。     

胭脂红荧光光谱机理研究

胭脂红是食品添加剂中最常用的一种食用色素之一,国家标准对其在食品中添加的剂量有明确的规定,研究其荧光光谱特性具有一定的实际意义。文章分别从理论与实验上对220～400 nm不同激发波长下胭脂红标准溶液的荧光光谱进行了分析,结果表明,胭脂红可以产生较强的荧光,分别在420,530,635,687 nm波长处产生了4个荧光峰,各荧光峰的最佳激发波长也不尽相同,文章给出了相应的荧光光谱图。经研究认为胭脂红荧光是由—OH中的n电子的n→π*跃迁和奈环中的π电子的π→π*跃迁这两类跃迁而产生的,其中420 nm处的荧光峰是由n→π*跃迁产生的, 而530, 635和687 nm这3个波长处的荧光峰是由π→π*跃迁而产生的, 同时其4个波长处的荧光相对强度随激发波长的变化相对改变不同,文章分别从微观机理上给出了一定的解释。研究胭脂红的荧光光谱及其特性可为其他偶氮类色素的荧光光谱研究提供参考,同时能为食品安全检测提供新的方法与途径。     

镧系配合物的荧光光谱

对镧系配合物荧光光谱的研究进展进行了评述,并对其光物理、光化学进行了归纳、分类,特别是对目前研究非常活跃的镧系离子荧光探针法在配合物和生物分子体系结构探测中的应用情况进行了总结。     

新型含芘荧光探针分子与蛋白质相互作用的光谱研究

利用荧光发射光谱和紫外-可见吸收光谱,研究了新型含芘荧光探针分子芘丁酰谷氨酸(PLE)和芘甲酰谷氨酸(PYE)与溶菌酶(Lyso)和牛血清白蛋白(BSA)的相互作用,分析了结合过程和机理。结果显示:不同间隔链长度的探针分子在与Lyso作用时,表现的光谱性质差别不大,这主要是由于探针分子结合到了Lyso的表面;而不同间隔链长度的探针分子在与BSA作用过程中,却表现不同的光物理性质,这可能是探针分子作用于BSA空腔时其结合位点或者结合方式的不同引起的。目前的研究对揭示蛋白质分子的识别位点和定位切割具有重要的意义。     

基于密度泛函的甲醇和乙醇荧光特性研究

使用英国爱丁堡FLS920P荧光光谱仪,对甲醇、乙醇的紫外吸收光谱和荧光光谱进行实验检测,得到二者的光谱特征参数。分别采用密度泛函理论(DFT)和单激发组态相互作用(CIS)对二者分子的基态和激发态结构进行优化,并比较两种分子在不同能态下的差异。应用含时密度泛函理论(TD-DFT)的不同泛函结合极化连续介质模型(PCM)在6-31++G(d, p)水平上分别计算了二者的紫外吸收光谱和荧光光谱,与实验结果吻合。分析了甲醇、乙醇荧光产生机理,同时分析了不同泛函对于计算光谱的影响。结果表明：甲醇、乙醇在紫外波段有微弱吸收,在紫外激发下能产生拉曼峰和微弱的荧光峰。甲醇、乙醇的吸收光谱是由里德堡激发产生,产生荧光的轨道跃迁为σ*→π*。泛函OLYP能够较好地重现实验吸收能,而泛函MPWK能够较好地重现实验发射能,并且发现不同的纯泛函计算跃迁能也具有差异性。结果可为醇类分子的分子特性研究提供参考。     

3种 β-巯基乙胺类席夫碱分子荧光光谱的量子化学研究

文章采用量子化学B3LYP方法,在6-31g基组水平下对3种β-巯基乙胺席夫碱进行几何构型优化,经振动分析,均未出现虚频率。在此基础上用TD-DFT方法计算了3种化合物的荧光光谱,所得计算值与实验值基本相符。理论计算表明,巯基乙胺类席夫碱化合物是性能较好的发光材料。     

3种对苯二甲醛类巯基席夫碱分子荧光光谱的量子化学研究

采用量子化学B3LYP方法,在6-31G基组水平下对3种对苯二甲醛类巯基席夫碱进行几何构型优化,经振动分析,均未出现虚频率。在此基础上用TD-DFT方法计算了3种席夫碱化合物的荧光光谱,所得计算值与实验值基本相符。理论计算表明,对苯二甲醛类巯基席夫碱是一类荧光性质较好的荧光化合物。     

黄酒的荧光光谱研究

黄酒有5000多年的悠久历史,是中国特色的酒类,被称为“国酒”,绍兴黄酒在中国黄酒中具有代表性。实验发现,绍兴加饭系列黄酒在适当的紫外波长激励下产生荧光光谱,文章运用三维等高线和二维荧光分析方法给出了整体和细部的比较分析。得出三种陈年黄酒在波长400～680 nm范围内存在较宽荧光峰的荧光光谱。3年陈、5年陈、8年陈酒的荧光峰分别在504, 488, 505 nm,最佳激发波长都在370 nm附近。初步阐述了其产生荧光的机理,解释了三种年份黄酒荧光图谱的相似与区别,并分析了产生较宽荧光峰的原因, 为黄酒的特征标识、品牌鉴定、年代鉴别、黄酒食用安全等研究提供了有科学意义的参考。     

Microwave spectra of CD3OH methanol

The microwave spectrum of CD₃OH has been studied over the 8 to 58 GHz region, and numerousb-type transitions have been assigned. Many of these belong toP subbranches which descend to the microwave region from subband origins lying much higher in the far-infrared, pass through zero frequency, and return upward again. Others are members ofb-typeQ branches which extend across the region. As well, variousa-typeK-doublet lines arising as transitions directly across the split levels of asymmetry doublets have been identified.     

掺稀土离子激光玻璃荧光光谱的测量

介绍了荧光光谱测量系统的测量原理,讨论了激发光源、单色仪光栅、样品的制备、激发光的激发位置和入射角、探测器、荧光光谱波段等测量条件的选取对激光玻璃荧光测量结果的影响。实验表明,在掺稀土离子激光玻璃荧光光谱的测量中,只有选取合适的测量条件,才可获得准确、可靠的测试结果。     

High-resolution far-infrared spectroscopy of C-13 methanol

The high-resolution far-infrared (FIR) Fourier transform spectrum of¹³CH₃OH has been studied from 25–350 cm^–1, andb-type^rR-branches in the torsional ground state have been assigned. The branches have been fitted to phenomeno-logical expansion parameters, which reproduce the branch frequencies generally to well within ±0.001 cm^–1. An interesting and relatively novel K=4 perturbation, localized to levels around J=18, has been observed between (nK)=(019) and (125) states.     

Anharmonic spectra of methanol and silanol: A comparative study

Anharmonic vibrational spectra of methanol and silanol as well as of some of their deuterated isotopomers are analysed using the vibrational self-consistent field approximation corrected by second order perturbation theory (cc-VSCF). Experimental frequencies in the case of methanol and its isotopomers are in general reproduced and anharmonic effects in their vibrational spectra are suitably explained. The similar species containing Si, i.e., silanol, is very unstable. Experimental data about its vibrational spectra are rare in the literature and the only theoretical data available come from the harmonic approach. Thus, to predict further anharmonic effects in its vibrational spectra, we extend our results on methanol to the silanol molecule.     

X-ray spectra of high temperature tungsten plasma calculated with collisional radiative model

Tungsten is regarded as an important candidate of plasma facing material in international thermonuclear experimental reactor （ITER）, so the determination and modeling of spectra of tungsten plasma, especially the spectra at high temperature were intensely focused on recently. In this work, using the atomic structure code of Cowan, a collisional radiative model （CRM） based on the spin-orbit-split-arrays is developed. Based on this model, the charge state distribution of tungsten ions is determined and the soft X-ray spectra from high charged ions of tungsten at different temperatures are calculated. The results show that both the average ionization charge and line positions are well agreed with others calculations and measurements with discrepancies of less than 0.63% and 1.26%, respectively. The spectra at higher temperatures are also reported and the relationship between ion abundance and temperature is predicted in this work.     

Structure of molecular associates of fluorescent probes in solutions of human serum albumin

Spectral-luminescent characteristics and molecular association processes in solutions of human serum albumin are analyzed at different pH values for three fluorescent probes (eosin, erythrosin, and fluorescein). Common features for all three probes in protein solutions are quenching of the fluorescence, a red shift of the fluorescence maximum, a decrease in the degree of association, and an increase in the angle between dipole moments of dye molecules in dimers. This being so, differences between fluorescein and its halogen derivatives (eosin and erythrosin) are observed in the pH dependences of fluorescence, degree of association, and the angle between dipole moments of probe molecules in dimers. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 782–787, November–December, 2008.     

Vibronic spectra of aluminium monochloride relevant to circumstellar molecule

The A^1Π→ X^1Σ^+ transition system of aluminium monochloride is determined by using ab initio quantum chemistry.Based on the multi-reference configuration interaction method in conjugate to the Davidson correction(MRCI + Q), the potential energy curves(PECs) of the three electronic states are obtained. Transition dipole moments(TDMs) and the vibrational energy levels are studied by employing the aug-cc-pwCV5Z-DK basis set with 4220-active space. The rovibrational constants are first determined from the analytic potential by solving the rovibrational Schr ¨odinger equation, and then the spectroscopic constants are determined by fitting the vibrational levels, and these values are well consistent with the experimental data. The effect of spin–orbit coupling(SOC) on the spectra and vibrational properties are evaluated.The results show that the SOC effect has almost no influence on the spectroscopic constants of AlCl molecules. For the A^1Π→ X^1Σ^+transition, the highly diagonalized Frank–Condon factor(FCF) is f(00)=0.9988. Additionally, Einstein coefficients and radiative lifetimes are studied, where the vibrational bands include ν'= 0–19→ν'=0–9. The ro-vibrational intensity is calculated at a temperature of 296 K, which can have certain astrophysical applications. At present, there is no report on the calculation of Al Cl ro-vibrational intensity, so we hope that our results will be useful in analyzing the interstellar Al Cl based on the absorption from A^1Π→ X^1Σ^+.     

飞秒激光作用下异质结的线性吸收谱研究

以二奈嵌苯分子吸附在TiO₂表面所组成的异质结构为例,介绍了在飞秒激光作用下由染料分子和半导体组成的异质结构中从分子基态到半导体导带的超快电子传输过程,在理论上分析了分子内部传输和直接电子传输过程对线性吸收谱的贡献.与分子内部传输过程项相比较分析了电子的超快直接传输在不同的分子及半导体结构下对线性吸收谱的影响. 关键词： 飞秒激光 线性吸收谱 超快电子转移     

Ultrasensitive fluorescent probe for copper ion based on cadmium selenide/cadmium sulfide quantum dots capped with dimercaprol

A new ultrasensitive copper ion fluorescent probe based on cadmium selenide/cadmium sulfide quantum dots capped with dimercaprol is described. Dimercaprol was bonded to the quantum dots through a surface ligand exchange to form dimercaprol-capped quantum dots whose fluorescence could be quenched by the coordination of dimercaprol on quantum dots’ surface with copper ion. The fluorescent probe based on dimercaprol-capped quantum dots showed a very good linear response range to copper ion from 0.1 to 50?µg?L^?1 with the detection limit of 0.087?µg?L^?1. The proposed method exhibited excellent sensitivity and selectivity due to the specific and strong affinity of dimercaprol with copper ion and the unique photoluminescence properties of quantum dots. The possible quenching mechanism was discussed and the probe was successfully applied to the determination of ultratrace copper in real samples.