光电子能谱与同系能级线性规律(Ⅱ)——同系非共轭体系

本文在文献[1]的基础上,进一步研究了正烷烃C_nH_2n+2及其它19个非共轭体系的60组光电子能谱,发现它们的各级垂直电离势也符合同系能级线性规律或同系线性规律,但线性相关系数前者比后者更好一些。     

光电子能谱与同系能级线性规律(Ⅲ)——双向延伸体系

研究了十一个双向延伸体系的四十八组光电子能谱数据,发现它们的各级垂直电离势符合同系能级线性规律,线性相关系数优良率为95.8％,用由光电子能谱得到的有关电离势,讨论了Π₄⁴的超共轭效应。     

有机同系物的指数型同系线性规律（Ⅰ）—光电子能谱数据的验证

本文提出一种未报道过的指数型同系线性规律，其表示式为：Ｐ＝ａ＋ｂｅｘｐ｛（ｋ＋１）／（２Ｎ＋３）｝用有机共轭同系物和非共轭同系物的光电子能谱数据对该线性规律进行了验证。     

直链共轭高分子的分子轨道理论(Ⅱ)——共轭体系的同系线性规律

应用差分方程法讨论了一类单连直链共轭高分子的本征方程的分解表达式。提出近似模型,用插入法得到具有交替键长的完整共轭多烯的能级和分子轨道的解析表达式,使许多单连同系列共轭分子的电离势线性关联,包括不同的能级都可用统一的参数处理。对双连体系做了类似研究,并提出了相关系数的严格评定判据。     

三岔共轭体系中的结构效应(Ⅵ)——氮杂查耳酮类化合物红外光谱中的同系线性规律

本文合成并研究了2P0nB、4P0nB、2Q0nB等11个三岔共轭化合物的红外光谱。实验表明这些化合物的基因特征吸收波数近似地遵守同系线性规律,相关系数r为0.982-1.000,与相应线性体系的同系直线比较,它们的斜率较小。这表明一个分岔的引入导致基因特征吸收波长红移,并表明在三岔体系中是分子整体性占优势而分岔基团的特性是受到分子整体性制约的。     

共轭体系分子轨道能的共振同系规律

同系线性规律已有较多研究.最近戴乾圜等用共振论阐释了同系线性规则,提出了共振同系因子,并用式(1)计算了电子吸收光谱数据的线性相关性.     

光电子能谱(一)

本讲座对光电子能谱在有机化学领域中的应用作了较全面的介绍。首先论述了它的基本原理和实验方法,然后对有机分子及其结构、高分子和聚合物、有机金属络合物、生物大分子等方面的使用方法和应用概况作了具体说明,希望能给从事有机化学研究的科技工作者,在方法上对它有一个较为全面的了解。     

光电子能谱(二)

二、实验方法 1.仪器能量定标刚离开样品的光电子的动能范围比较大(如在MgKa激发下,0～1250 eV),进入能量分析器的光电子的动能范围,由于透镜减速,已大大缩小(如0～65 eV)。由此,光电子由于动能变化引起的质量变化很小,以至于可把经过分析器的光电子的质量看作常数,从而使光电子能量与分析器电压有比较好的线性关系。分析器电压由基准电源控制的扫描高压发生器供给,基准电源又受到定标电路的调节。调节定标电位器,使分析器电压和能量读数之间的比例系数为1,这就是每台电子能谱仪在投入使用之前,必须做的能量定标工作。     

光电子能谱(五)

3.配位络合物在过渡金属原子形成的阳离子周围,由一些中性分子和(或)阴离子所环绕,从而生成具有一定形式的配位络合物,这些中性分子及阴离子就称为配位体。配位体的活性有赖于中心离子的性质。配位体接近带高电荷的金属中心离子时,引起分子中的极化,或当配位体将它的电子供给一个阳离子共享后就会发生许多变化,其中最重要的是使给电子原子上的其它键减弱。一系列电子给予体和金属配位时,它将孤对电子或π电子输送给中心过渡金属的空d轨道成σ键,同时充满电子的适当金属d轨道将电子回送给配位基的空反键轨道成dπ-pπ键。由于配位基的不同,金属氧化态的不同,σ给电子能力和π受电子能力有差异,因此金属配合物的活性及配位体中的键强也有差别。光电子能谱通过结合能的测定可以提供电荷转移的信息,成为研究配位键性质的一种工     

光电子能谱(四)

2.天然与合成高分子化合物用光电子能谱研究高分子化合物,所得数据一般不及红外和核磁来得精细,但具有快速、方便和不破坏表面等优点。对难溶的聚合物或经各种化学和物理处理的高分子化合物表面(如氧化、氟化、溶剂或等离子体处理),以及聚合物的光降解,等离子聚合和辐射接枝等过程进行研究,可以获得许多有价值的信息。有些问题是用其它分析方法无法解决的。 2.1 表面处理 2.1.1.试剂处理使织物阻燃为了赋于棉织物良好的阻燃性能,可以先用 tetrakis (hydroxymethyl) phosphonium     

查尔酮类共轭体系电子光谱及线性关系的MHMO法计算

对查尔酮类共轭体系的电子光谱,CNDO/2计算及线性关系文献中已作了全面报道。本文用林惠心等在徐光宪改进的HMO法基础上提出的改进HMO法(即MHMO法),对查尔酮类共轭体系进行了计算,结果λ_计和λ_实基本一致,线性关系良好。     

同系规律的联系和比较

本文由同系能级线性规律E=a+b(2k-1)/ksin(kπ/(2N+1))推导出了文献[6]提出的同系递变规律E=a+b/N,在推导的过程中得到一个新的比同系递变规律好的同系函数E=a+b((2k-1)/(N+1/2)).用文献[2][9]发表的96组光电子能谱数据和文献[1]发表的159组电子光谱数据对最近提出的五种同系规律进行了检验、比较,我们认为同系能级线性规律比较好。     

键轨道线性组合分子轨道法与有机共轭分子的结构

本文提出了键轨道线性组合分子轨道(LCBOMO)法,并用这个方法处理若干类型交替烃的Π键结构。给出同系物分子Π电子能量、波函数以及键级的通式。阐述了共轭能和成环能产生的根据。LCBOMO法使用价键模型,计及了"π键"间的相互作用,得到与共轭效应符合的结果,因而对价键理论有所发展。     

DETERMINATION OF THE IN VIVO ABSORPTION AND PHOTOSYNTHETIC PROPERTIES OF THE LICHEN Acarospora schleicheri USING PHOTO ACOUSTIC SPECTROSCOPY

Photoacoustic spectroscopy was used to determine the in vivo spectra of the stratified components of the lichen Acarospora schleicheri. There were three pigmented layers observed by the photoacoustic method: an absorption band associated with the pigment rhizocarpic acid, a bulk cytochrome absorption, and the absorption of the algal chloroplast. Due to the different absorption properties of these distinct layers, the photoacoustic technique was able to monitor the physical effect of hydration on the lichen. Hydration of the lichen reduced the scatter of the sample, increasing the effective incident light intensity within the sample. Hydration also resulted in an increase in the optical absorption coefficient of the algal layer, which was interpreted as a movement of the algal chloroplast in response to low light fluence and hydrated conditions. The photoacoustic technique was also used to monitor the relative photosynthetic activity of the algae within the lichen in a hydrated and dehydrated state. The photosynthetic assay could detect photosynthetic activity in the hydrated state but not in the dehydrated state. In addition, the photosynthetic response was found to be induced and repressed with light and dark periods respectively and its detection was limited at high frequencies by the damping of the thermal wave from the algal layer.     

A LASER FLASH SPECTROSCOPY STUDY OF THE KINETICS OF ELECTRON TRANSFER FROM SPINACH PHOTOSYSTEM I TO SPINACH AND ALGAL FERREDOXINS

Laser flash absorption spectroscopy has been used to investigate the kinetics of electron transfer from P700 in Photosystem I (PSI)-enriched particles from spinach to the ferredoxins from spinach and the green alga Monoraphidium braunii. Very similar behavior for the interaction of both ferredoxins with the PSI complex was observed, although the algal ferredoxin appears to be slightly more effective as an electron acceptor. For both proteins, a non-linear protein concentration dependence of the rate constant for reduction was obtained, indicating complex formation preceding electron transfer. Estimates of 3 times 10⁷M^?1 s^?1 and 140–180 s^?l were obtained from these data for the second order rate constants for complex formation, and the limiting first order rate constants for electron transfer, respectively. At neutral pH, a biphasic dependence of the rate constant for ferredoxin reduction on the concentration of NaCl or MgCl₂ was observed. This was interpreted in terms of the electrostatic interactions which occur between ferredoxin and the PSI membrane. In addition, magnesium cations appear to play a specific role in the interaction between PSI and ferredoxin. Thus, the addition of these ions under optimal conditions induces a 6-f-old increase in the electron transfer reaction rate constant, compared with a 2-f-old increase in the presence of an optimal amount of NaCI. This cannot be explained as arising from ionic strength effects. To our knowledge, this is the first time that a direct measurement of the rate constant for the reduction of ferredoxin by the PSI complex has been reported.     

以聚醚链相连的9-氨基吖啶、苯甲酸酯二元体系的合成及分子内光诱导电子转移反应

本文用聚四乙二醇柔性链将9-氨基啶和不同取代基的苯甲酸酯连接起来,合成了一类新型二元分子体系。对各体系中9-氨基啶的电子转移荧光猝灭进行了研究,并根据稳态荧光猝灭计算了体系中的荧光猝灭效率和荧光猝灭速率常数。     

INVESTIGATION OF MIGRATION PARAMETERS OF ELECTRON EXCITATION ENERGY IN PHOTOSYNTHETIC and ARTIFICIAL SYSTEMS

Abstract— The technique for the determination of diffusion parameters on the basis of nonlinear fluorescence quenching and excitation energy capturing by the traps is discussed. The nonstationary character of the processes of excitation capturing by traps and of singlet-singlet annihilation which occur upon the system excitation by a picosecond pulse is taken into account. The obtained values of the diffusion parameters in the artificial pigment-polymer antenna system (the diffusion coefficient ∼ 10^-2 cm² s^-1 and the diffusion length ∼ 500 Å) are close to those in the photosynthesizing systems. It is also shown that the method of the determination of diffusion parameters on the basis of excitation capturing by the reaction centres may be applied for the study of the native photosynthetic systems.     

碘鎓盐/胺体系基态和激发态的光谱研究

研究了碘鎓盐与胺在基态和激发态的相互作用,观察到它们形成以鎓盐为电子受体和胺为电子给体的基态和激发态电荷转移络合物。测定了二苯基碘鎓盐和三乙胺形成的络合物组成为1:1分子比,其缔合常数和克分子吸收系数分别为2.2×10mol^-1和2.8×10³mol^-1·1·cm^-1。实验结果表明,随着胺的给电性增加,电荷转移络合物的吸收波长红移,胺的空间体积增大,由于空间障碍,电荷转移络合物的克分子吸收系数下降。     

ON THE POSSIBILITY OF GENERATION AND TRANSFER OF ELECTRONIC ENERGY IN BIOCHEMICAL SYSTEMS

Abstract— Generation of electronically excited species is a distinct possibility in biological systems; the most likely ones at present appear to be flavins, metalloporphyrins, oxygen and certain conjugated carbonyl compounds. Thyroxine should be very active in certain cases of electronic energy transfer.     

SPECTROSCOPY OF CHLOROPHYLL IN BIOLOGICAL AND SYNTHETIC SYSTEMS*

Abstract. –This review discusses recent spectroscopic studies aimed at discovering the structure, orientation, and function of chlorophyll in vivo. In plant membranes there appear to be at least two distinct types of chlorophyll a. The greater part, over 99%, is antenna chlorophyll which absorbs and transfers radiant energy to a few specialized chlorophyll molecules in a reaction center where the actual charge separation occurs. A dimer-oligomer model for antenna chlorophyll has been proposed on the basis of comparative studies of the absorption spectra of chlorophyll in various dry solvents and in vivo. Unfortunately a similarity between essentially structureless broad spectra is very weak evidence for their original identity. Also the requirement of an anhydrous environment for most of the chlorophyll in biological material is an unlikely postulate. A cross-linked, linear polymer model of chlorophyll in vivo has also been proposed. Recent Resonance Raman spectroscopic results appear to rule out, in large part, either polymer model and once again suggest that it is the various attachments of chlorophyll to proteins which determine its function as antenna pigment in vivo. Circular dichroism measurements of chlorophyll in various plant materials have also led to the conclusion that antenna chlorophyll has strong interaction with protein. However, some doubt still exists as to the interpretation of these CD results. New studies of fluorescence, polarized fluorescence and Resonance Raman spectroscopy of various plant species corroborate the original proposition, based upon deconvolution of absorption spectra, that antenna chlorophyll occurs in vivo in at least five discrete pools, and that each pool is likely to be located in the same environment in different plants. A new model-systems approach to simulating chlorophyll in vivo has come through the use of lipid bilayers and liposomes. Charge transfer has been observed between chlorophyll in a lipid phase and phycobiliproteins or cytochrome c. The most promising, newly synthesized model for the reaction center, P700, is a covalently bound dimeric derivative of pyrochlorophyllide a. Its properties are similar to P700 in several respects except for reversible photooxidation which has not yet been observed. By detergent treatments chlorophyll-protein complexes having about 20–40 chlorophyll a molecules for every P700 have been isolated from different plants, and their spectroscopic properties are under investigation in several laboratories. The several hypotheses to explain the shape of the oxidized minus reduced absorption difference spectrum of P700 have not yet been reconciled. The nature of the photosystem II reaction center chlorophyll, P680, is also a subject of active investigation. Its absorption difference spectrum appears to have two kinetic components.