基于波长调制光谱技术的氧气浓度检测及其标定方法

提出了一种基于激光波长调制光谱(WMS)技术检测氧气浓度的方法,理论上推导出二次谐波的线型表达式,搭建氧气浓度实验系统,确定了相关实验参数。采集10种不同氧气浓度的样本,利用氧气分子位于13142.58 cm-1的吸收谱线进行测试,分别用二次谐波幅值、二次谐波与一次谐波的幅值比来反演氧气浓度,后者拟合系数达0.9973,相比前者的标定方法提高了1.49%。     

ZrO2：Er^3＋，Yb^3＋纳米晶的制备及Er^3＋离子能级在晶体场中的分裂

采用1，3-丁二醇低热结晶法制备了ZrO2：Er^3 ，Yb^3 纳米晶．常温下，用980nm的红外激光激发可以观察到很强的ZrO2：Er^3 ，Yb^3 纳米晶红光发射，用荧光光谱仪记录了该上转换光谱．X射线粉末衍射(XRD)结果表明，ZrO2：Er^3 ，Yb^3 纳米晶属于立方晶系．研究了纳米晶的上转换发光机理，根据晶体场理论对Er^3 的2个上转换能级进行了Stark分裂计算，对2个能级之间的谱线进行了归属，进一步证实了980nm激发Er^3 离子的上转换经历两个过程：一是连续吸收2个980nm光子的过程，二是吸收980nm光子，电子转移到亚稳态能级后，再吸收980nm光子的过程．     

原子吸收光谱中的三磁场塞曼背景校正技术

1　塞曼效应原子吸收光谱分析测量被分析元素基态原子对分析元素共振线的吸光度。但是除了被分析元素的共振吸收外 ,通常还有背景吸收 ,必须予以扣除或校正 ,才能获得准确的结果。塞曼原子吸收光谱仪利用塞曼效应作背景校正。当光源置于强磁场内时 ,光源辐射的谱线发生分裂 ,称为塞曼效应或塞曼分裂。分裂产生中心波长不变的π组分和对中心波长频移的σ +、σ -组分 ,该频移称为洛伦茨裂距。π组分和σ±组分有相互垂直的偏振方向。塞曼效应有正常塞曼效应和反常塞曼效应之分 :正常塞曼效应分裂出一条π组分和 2条σ组分(一条σ+和 -条σ -)…     

CO2对790nm附近水线的压力加宽和位移

采用高灵敏的激光光腔衰荡光谱技术研究了CO2对160水分子v^2＋3v^3振动带跃迁线的压力诱导效应．为了抑制水的自碰撞效应,水的压力在实验中低于0．5Torr．基于铷原子吸收线和超稳法布里-珀罗标准确定了跃迁谱线高达10^-5cm^-1精度的绝对频率．采用软碰撞模型对吸收线进行模拟,获得了对应的线形参数．     

小波变换三波长系数倍率法同时测定钒,钼和钛

ｌ引言芦丁作为显色剂，能与几种金属离子形成灵敏度较高的络合物，但吸收光谱严重重叠而彼此严重干扰各自的测定．本文用小波变换对吸收光进进行处理．滤去适当的高频噪声，再用三波长系数倍率法进行计算处理，使得广了同时测定钒、钼、钛三组分成为可能，结果满意．２实验部分２．１主要仪器与试剂７５３０Ｇ分光光度计，５８６微机．金属离子标准溶液，芦丁乙醇溶液，溴化十六烷基三甲铵水溶液，ＨＡｃ－ＮａＡｃ缓冲溶液．２．２实验方法分别移取一定量的钒、钼、钛标准溶液于２５ｍＬ容量瓶中，依次加入２．０ｍＬ１．０×１０－３ｍｏ…     

磺化2,3-萘酞菁锌(Ⅱ)、钴(Ⅱ)的电子吸收光谱和荧光光谱的研究

研究了磺化2，3-萘酞菁锌(Ⅱ)、钴(Ⅱ)在DMF(N，N-二甲基甲酰胺)、DMSO(二甲基亚砜)、乙醇、水等溶剂中的电子吸收光谱和荧光光谱．萘酞菁配合物的Q带与相应的酞菁配合物Q带相比，电子吸收光谱红移80～90nm，荧光光谱红移约100nm，荧光强度也显增加．在金属萘酞菁中引入磺酸基，配合物的电子吸收光谱Q带发生红移，但是影响不大、对于相同中心金属的配合物，改变溶剂的种类对配合物的电子吸收光谱的Q带影响较大．在金属萘酞菁环上引入一个磺酸基时，在相同溶剂中与无取代萘酞菁相比发生荧光光谱Q带红移，荧光强度增大．但在萘酞菁环上继续引入磺酸基时，荧光强度反而减少．磺化萘酞菁钴比磺化萘酞菁锌有较大的荧光强度．不同浓度下的电子吸收光谱和荧光光谱说明金属萘酞菁有集聚倾向、能形成基激缔合物．     

三异丙氧基混合稀土掺杂改性聚苯乙烯的研究

用廉价的三异丙氧基混合稀土杂改性聚苯乙烯，利用红外光谱，紫外与可见光吸收光谱，荧光光谱，X射线光电子能谱，扫描电镜等手段对其表下，并测定其冲击强度。证明了改性聚苯乙烯中存在着稀土金属离子与苯环的配位作用；改性聚苯乙烯的荧光强度比纯聚苯乙烯的高，其中以稀土含量为1．0％时其荧光强度最高，同时改性后聚苯乙烯抗冲性能显著提高，表明三异丙氧基混合稀土对聚苯乙烯有较好的增韧作用。     

NaYF4∶Er3＋, Yb3＋纳米晶的液相合成

采用丙三醇液相结晶法制备了NaYF4∶Er3＋, Yb3＋上转换纳米晶, 合成步骤被简化. 常温下, 用980 nm的红外激光激发可以观察到很强的绿光、红光发射, 用荧光光谱仪记录了该上转换光谱. X射线粉末衍射(XRD)结果表明, 该方法制备NaYF4∶Er3＋, Yb3＋纳米晶属于立方混合六方晶系. 研究了纳米晶的上转换发光机理, 根据晶体场理论对Er3＋的两个上转换能级进行了Stark分裂计算, 对两个能级之间的谱线进行了归属, 进一步证实了980 nm光子激发Er3＋离子的上转换机理, 一个是连续吸收两个980 nm光子的过程(激发态吸收), 另一个是吸收980 nm光子后, 电子转移到亚稳态能级, 然后再吸收980 nm光子过程(能量转移上转换).     

偶极-偶极相互作用的探讨(I)

用增强拉曼光谱和电势调节红外光谱探讨偶极－偶极相互作用时，吸附带强度变化比频率位移更为重要．因为其它因素，如吸附物位置不均匀，通过金属表面的诱导作用等也能引起频率的稍微位移，但这些因素均不能解释强度转移效应．分子间的振动相互作用主要通过它们的偶极场，吸附分子吸收峰强度的转移与它们的电子极化率的屏蔽作用密切相关，相关势近似（CPA，CoherentPotentialApproximation）已广泛用于讨论分子间的振动相互作用［1］．本文用CPA方法计算了C（ZXZP’CN一、“CN丫All（100）体系的吸收光谱，并与吸附在粗化金电极上的…     

低浓度样品拉曼光谱的实验研究

在液芯光纤内产生共振拉曼效应,可以提高拉曼光谱强度１０＾９倍。测定了１０＾－１０－１０＾－５ｍｏｌ／Ｌ浓度样品的拉曼光谱。实验结果表明,β－胡罗卜素在ＣＳ２中１５２０ｃｍ＾－１拉曼线的强度（散射系数）、频移、线宽随浓度降低而发生变化。     

Kinetics of emulsion polymerization

The quantitative theory of the free-radical mechanism in emulsion polymerization is reexamined. A mechanism involving desorption and reabsorption of radicals is discussed. The average number of radicals per particle has been calculated as a function of three parameters. A simplified, approximate solution for the average number of radicals per particle is given for cases where this number is low.     

The observation of the first vibrational overtone of dihydrogen in the luminescence of zeolites at low temperatures

Dehydrated zeolites NaA, NaY, and barium-exchanged NaY luminesce when irradiated with the 1064 nm laser light of an FT-Raman instrument. When hydrogen is adsorbed in the zeolite, the luminescence is altered in several ways. Most remarkable is the appearance of "absorptions" in the positions of the first vibrational overtones of H(2) and HD. Although these features are in the expected positions with reasonable band profiles for overtone absorptions, the large extinction of the luminescent intensity requires a more efficient mechanism than simple reabsorption of emitted photons. In addition to the appearance of holes in the luminescence spectrum, other luminescent features are substantially quenched by the presence of hydrogen or, in one case, augmented.     

TiO2光催化降解4-氯苯酚过程中的电分析监测

采用循环伏安法和紫外光谱法对有机物的光催化降解进行机理研究和在线监测.以标准光催化剂DegussaP25在紫外光照射下催化降解4-氯苯酚,发现在降解过程中至少有两对氧化还原中间产物对苯二酚-苯醌和羟基氢醌-羟基苯醌.由4-氯苯酚及中间产物的电极响应,可以观测到它们在光催化降解过程中的含量变化,从而对整个过程实现在线监测,并由此全面了解光催化反应机理.从不同反应时间后测得的紫外光谱可以看到,苯环特征峰逐渐消失.这表明4-氯苯酚的苯环逐渐被打开,直至被彻底降解.     

The effect of anticancer drugs on seven cell lines monitored by FTIR spectroscopy

Systemic approaches such as metabolomics are increasingly needed to improve the development of novel drugs. In this paper, we suggest a new strategy based on infrared spectroscopy which probes the global chemical composition of a sample. Seven cell lines from three tumour types were investigated and exposed to four classical anticancer drugs belonging to two classes characterized by a unique mechanism. First, each cell line was considered separately and a hierarchical clustering was built for the seven cell lines. Spectra clustered according to the drug mechanism of action for all the cell lines tested. Second, the similarities among drug mechanism spectral fingerprints were investigated for all the cell lines simultaneously. Difference spectra (the mean spectrum of the corresponding untreated cell line was subtracted) were computed so that the particular contribution of every cell line was eliminated and only the drug-induced differences could be compared. The hierarchical clustering shows a clear tendency to distinguish the two modes of action, revealing a very similar type of response to molecules with a similar mechanism. High throughput systems with 96-well plates are now available and a well established bioassay could be developed in order to provide an objective classifier for potential anticancer drugs.     

Quantitative fluorescence excitation spectra of synthetic eumelanin

Previously reported excitation spectra for eumelanin are sparse and inconsistent. Moreover, these studies have failed to account for probe beam attenuation and emission reabsorption within the samples, making them qualitative at best. We report for the first time quantitative excitation spectra for synthetic eumelanin, acquired for a range of solution concentrations and emission wavelengths. Our data indicate that probe beam attenuation and emission reabsorption significantly affect the spectra even in low-concentration eumelanin solutions and that previously published data do not reflect the true excitation profile. We apply a correction procedure (previously applied to emission spectra) to account for these effects. Application of this procedure reconstructs the expected relationship of signal intensity with concentration, and the normalized spectra show a similarity in form to the absorption profiles. These spectra reveal valuable information regarding the photophysics and photochemistry of eumelanin. Most notably, an excitation peak at 365 nm (3.40 eV), whose position is independent of emission wavelength, is possibly attributable to a 5,6-dihydroxyindole-2-carboxylic acid (DHICA) component singly linked to a polymeric structure.     

聚乙二醇催化下的反常Reimer—Tiemann反应

自1876年Reimer-Tiemann反应(以下简称R-T反应)提出后,许多化学工作者曾对该反应进行了深入研究。1988年丁新腾等又报道了叔胺存在下的反常R-T反应。但以聚乙二醇(PEG)为相转移催化剂,催化R-T反应未见报道。本文报道了无水相存在下PEG催化的反常R-T反应,并对其催化行为从理论上进行了探讨。     

Study of anomalous infrared properties of nanomaterials through effective medium theory

Effective medium theory is introduced into a three-layer model to study the anomalous IR properties of nanostructured Pt films. A composite system is set up for the nanostructured film together with adsorbates and water around it. The anomalous IR spectral features, which exhibit a transition from enhanced (or normal) IR absorption to Fano-type bipolar line shape and, finally, to enhanced anomalous IR absorption (the abnormal infrared effects) along with the change in structure and size of nanomaterials, as observed through experiments for CO molecule adsorption, are elucidated by an increase in the volume fraction of metal in the composite system and the effective thickness of the composite system. The theoretical simulation results illustrate that the spectral line shape of IR absorption depends strongly on the volume fraction of metal, while the intensity of the IR band is directly proportional to the effective thickness. This study has revealed, through a physical optical aspect of interaction of CO molecules with nanostructured metal films, one of the possible origins of anomalous IR properties and has shed light on interpreting the peculiar properties of nanomaterials.     

The vacuum and oxidative pyrolysis of poly-p-xylylene

Poly-p-xylylene prepared by pyrolysis of di-p-xylylene has been degraded under vacuum and in the presence of oxygen as a function of temperature and oxygen pressure. The vacuum pyrolysis is mainly due to “abnormal” structures. Volatiles are initially produced quite slowly, but the reaction accelerates subsequently. Arrhenius equations were derived for various ranges of volatile formation. A mechanism has been formulated consisting of random chain scission followed by depropagation (dimers to pentamers); simulatanously another zip reaction produces hydrogen. The thermal, oxidative degradation has been studied above and below the softening point of the polymer as a function of oxygen pressure. A first-order reaction of volatile formation due to “abnormal” chain scission is followed by normal chain scission, which is also first order. The postulated mechanism leads initially to hydroperoxide formation. Arrhenius equations for volatile formation are different below and above the softening point. Oxygen consumption also follows a first-order reaction with an energy of activation of 31.5 kcal/mole.     

Enzyme ribonucleotide reductase: unraveling an enigmatic paradigm of enzyme inhibition by furanone derivatives

Several 2'-substituted-2'-deoxyribonucleotides are potent inactivators of the enzyme ribonucleotide reductase (RNR), by destroying the essential tyrosyl radical located in subunit R2 or/and covalently alkylating the subunit R1. In the absence of external reductants, the inactivation is achieved by alkylation of subunit R1 by a methylene-3(2H)-furanone. The furanone is generated in solution through degradation of a keto-deoxyribonucleotide intermediate, produced during the inhibitory mechanism of a wide group of 2'-substituted inhibitors, and is easily detected experimentally by UV spectroscopy. Interestingly, the same keto-deoxyribonucleotide is also a proposed intermediate of the normal substrate pathway, but by some unknown reason, it does not dissociate from the active site and does not inactivate the enzyme. Therefore, if the currently accepted mechanism for substrate reduction is correct, there must be some specific reason that makes such a reactive intermediate behave differently, not dissociating from the active site during substrate reduction. In this article, we propose to validate the current substrate mechanism by showing that the keto-deoxyribonucleotide dissociates from the active site only in the case of the inhibitors, and therefore, it corresponds to a viable intermediate in the substrate mechanism. Furthermore, we answer unexplained experimental observations that concern the predomination of the normal reduction mechanism over the abnormal ketone formation in the FdNDP and the release of F(-), either in the normal or in the abnormal turnover. For that purpose, we have investigated the interaction between the enzyme and this keto-deoxyribonucleotide generated from the normal substrate and from two widely studied representative inhibitors. A model containing 140 atoms was used to represent the desired structures. The results allowed us to conclude that the solvation free energy of the 2'-substituents, its influence inside the active site, and the charge transfer mechanism from a protein side chain to solution are the thermodynamic driving forces for the intermediate dissociation and subsequent RNR inhibition. Such charge transfer cannot be accomplished by the natural substrate, preventing its dissociation. These results elucidate a paradox which has been unexplained for more than 20 years and further validates both the proposed substrate and inhibition chemical mechanisms.     

Particle nucleation in emulsion polymerization. III. Nucleation in systems with anionic emulsifier investigated by seeded and unseeded polymerization

Studies of seeded and unseeded polymerization of styrene using sodium dodecylsulfate as emulsifier have been carried out in order to investigate the mechanism of particle nucleation in such systems and to test the theory presented in Part I of this series. The rate of capture of water-soluble oligomeric radicals was considered to be governed by absorption of oligomers with chain length one less than the critical chain length. It was concluded that the micelles became the dominating loci for particle nucleation above CMC for the emulsifier. A complete nonsteady-state model for particle initiation above CMC which takes into account radical desorption and reabsorption has been developed. It was indicated that, even for styrene, desorption of radicals may play a role in controlling the radical and particle number of interval I under certain conditions. The model also showed that the efficiencies of particles in absorbing radicals could be calculated from physical parameters, such as diffusion constants and surface charge densities, which are available for the system.