d-core transitions in ZnTe,CdTe and HgTe

Summary We have measured the reflectivity spectra of monocrystalline ZnTe, CdTe and HgTe between 5 and 35 eV. We have interpreted the sharp structures above approximately 10 eV as transitions originating in the metal uppermostd levels. The structures give a picture of the projected densities of states of the conduction bands and supply a better understanding of their states.

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Riassunto Abbiamo misurato gli spettri di riflettività di monocristalli di ZnTe, CdTe ed HgTe tra 5 e 35 eV. Oltre i 10 eV gli spettri presentano delle strutture fini, interpretate come transizioni che hanno origine nei livellid piú alti del catione. Questa interpretazione permette di ricavare una rappresentazione schematica della densità proiettata degli stati di conduzione e di ottenere una migliore comprensione sulla natura degli stati finali stessi.

     

紫外光对NO_3~-还原作用的研究

紫外光对NO_3~-水溶液有很强的还原作用,能定量生成NO_2~-。该还原作用与光源强度、光照距离、照射时间、酸度、温度、共存物质等因素有关。选择合适条件能在10分钟内100%还原NO_3~-为NO_2~-。建立了优越得多的紫外光还原法代替镉柱还原法,成功地测定了水样中NO_3-。所得结果与镉柱还原法相符,相对标准偏差±1%,标准回收率98～99%。     

Molar absorptivity and A 1cm 1% values for proteins at selected wavelengths of the visible and ultraviolet regions. XXIV

The molar absorptivity and A _1cm ^1% values for 154 proteins are reported. The conditions under which these values were obtained and citations to the sources of the data are also provided.     

红外激光场中共振结构原子对极紫外光脉冲的压缩效应

通过数值求解一维原子的含时薛定谔方程, 研究了具有共振结构的原子在双色场(红外激光(IR)+极紫外光(XUV)) 驱动下发射高次谐波的特征. 研究结果表明, 具有共振结构的原子所发射的高次谐波与无共振结构原子(简称为一般原子)发射的高次谐波有明显不同, 共振结构的原子除了在某一能量附近(原子的共振能量+电离能)高次谐波的强度有很大提高外, 它还对XUV光的响应较一般原子表现得更为敏感, 即使XUV光的强度较弱, 也能够明显提高XUV光脉冲中心频率附近的谐波强度, 更重要的是通过调节双色场的时间延迟, 能使输入的XUV光的脉宽得到明显的压缩, 通过时间-频率分析给出了发生这种现象的原因. 由此提出了通过滤波-连续反馈的方式可使XUV光的脉冲从200 as压缩至120 as左右.     

紫外可见分光光度计的FDA仪器认证方法探讨

介绍紫外可见分光光度计符合FDA仪器性能认证的方法。主要对灯能量、吸光度的准确度和仪器线性等检定规程中没有或者确认方法不同的项目进行性能确认。分别在235,257,313,350 nm处,对重铬酸钾标准溶液进行测定,若吸收系数分别在123.0~126.0,142.8~146.2,47.0~50.3,105.5~108.5范围内,则仪器符合FAD认证要求;对系列重铬酸钾标准溶液进行测定,若吸光度与浓度的相关系数r2≥0.999,则仪器符合FAD认证要求。该认证方法可以保证紫外可见分光光度计性能正常,使测量结果准确、可靠。     

固相萃取/超高效液相色谱法测定纺织品中14种紫外吸收剂

建立了固相萃取(SPE)净化,超高效液相色谱(UPLC)同时测定纺织品中14种二苯甲酮类(BPs)和苯并三唑类(BZTs)紫外吸收剂的分析方法。样品以甲醇-四氢呋喃超声提取,提取液经ENVI-Carb固相萃取柱净化后,在C18色谱柱和乙腈-0.1%甲酸水流动相下梯度洗脱分离,二极管阵列检测器测定。结果表明,14种紫外吸收剂在0.1~50 mg/L浓度范围内线性关系良好,相关系数均大于0.999;方法检出限为1~5mg/kg;阴性涤纶和腈纶样品在3个加标水平下的平均回收率(n=6)为81.5%~99.1%,相对标准偏差(RSD)为2.8%~7.5%。该方法简单快速,回收率和精密度良好,适用于纺织品中14种紫外吸收剂的同时测定。     

聚乙烯醇缩酮化度的定量表征

本文在不同条件下制备出聚乙烯醇（ＰＶＡ）与丙酮的缩酮化产物ＰＶＫＴ。进一步利用核磁共振（＾１Ｈ－ＮＭＲ，＾１３Ｃ－ＮＭＲ）、红外光谱（ＩＲ）、紫外光谱（ＵＶ）三种测试手段建立了表征缩酮化度的方法，从不同角度分析了上述方法在表征缩酮化度的准确性。     

胶束增稳荷移反应紫外分光光度法测定洛美沙星

提出了一种基于胶束增稳荷移反应测定洛美沙星的紫外分光光光度法 ,研究了在阳离子表面活性剂溴化十六烷基吡啶 (CPB)胶束体系中电子给体洛美沙星与电子受体四氯对苯醌之间的荷移反应产物的紫外光谱性质。发现CPB对洛美沙星与四氯对苯醌的荷移反应络合物有显著的增稳效应。洛美沙星的浓度在0 .8～ 5 4mg L范围内符合比尔定律 ,r =0 .9994。在测定波长 32 3nm处 ,络合物的表观摩尔吸光系数为 3.5 6×10 - 4L·mol- 1 ·cm- 1 。本方法用于片剂中洛美沙星含量的测定 ,其回收率为 97.8%～ 10 0 .5 % ,相对标准偏差为0 .9%～ 2 .4 %。     

β-萘甲酰化β-环糊精的分子识别性能研究

最近二十年,外形似“锥简”,腔内疏水,脏外亲水的环糊精（Cyclodextrin,CD包括a,o,7－CD等）,以其特有的结构在模拟酶、分子识别等众多领域内深受广大科学工作者重视［’－‘］．为了获得更有效的模拟酶及分子识别功能体,我们已合成并报道了一系列含有发色基团的CD衍生物卜一句．本文利用基紫外光谱对产一茶甲酸化公CD的分子识别性能作了研究,结果显示3一位修饰CD（3一氧一八茶甲酸基一只CD）1对客体（环己醇）的包结性能是6一位修饰CD（6一氧一界禁甲酸基一八CD）2的4．4倍·结果还显示用环乙烷作客体时与主体正的包结和用…     

Ultraviolet curing of acrylic systems: Real‐time Fourier transform infrared,mechanical, and fluorescence studies

The photopolymerization of acrylic‐based adhesives has been studied by Fourier transform infrared and fluorescence analysis in real time. Real‐time infrared spectroscopy reveals the influence of the nature of the photoinitiator on the kinetics of the reaction. Furthermore, the incident light intensity dependence of the polymerization rate shows that primary radical termination is the predominant mechanism during the initial stages of the curing of the acrylic system with bis(2,4,6‐trimethylbenzoyl) phenyl phosphine oxide (TMBAPO) as a photoinitiator. The fluorescence intensity of selected probes increases during the ultraviolet curing of the adhesive, sensing microenvironmental viscosity changes. Depending on the nature of the photoinitiator, different fluorescence–conversion curves are observed. For TMBAPO, the fluorescence increases more slowly during the initial stage because of the delay in the gel effect induced by primary radical termination. Mechanical tests have been carried out to determine the shear modulus over the course of the acrylic adhesive ultraviolet curing. In an attempt to extend the applications of the fluorescence probe method, we have undertaken comparisons between the fluorescence changes and shear modulus. Similar features in both curves confirm the feasibility of the fluorescence method for providing information about microstructural changes during network formation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4236–4244, 2002