CdSe和ZnO量子点的拉曼光谱研究

本文介绍了用拉曼光谱研究CdSe和ZnO两种Ⅱ Ⅳ族量子点材料的结果,对拉曼峰进行了指认。观察到的光学声子峰位的移动被认为是由量子限制效应引起。     

Si衬底上ZnSe外延膜的低压MOCVD生长

以硒化氢（H2Se）和二甲基锌为源材料，生长温度是300℃时，用低压金属有机化学气相沉积（LP－MOCVD）系统在Si(111)衬底上外延生长了ZnSe薄膜。通过X射线衍射（XRD）、扫描电子显微镜的能量色散（EDS）以及光致发光（PL）实验验证ZnSe外延膜的质量，在X射线衍射谱中只有一个强的ZnSe(111)面衍射峰，这说明外延膜是（111）取向的单晶薄膜，在能量色散谱中除了Si,Zn和Se原子外，没有观测到其他原子，说明ZnSe外延膜中杂质含量较少。ZnSe外延膜中Zn/Se原子比接近1，有较好的化学配比。在ZnSe外延膜的77K光致发光谱中没有观测到与深中心发射相关的发光峰，表明ZnSe外延膜的晶格缺陷密度较小。77K时的近带边发射峰447nm在室温时移至465nm附近。     

ZnSe/SiO2复合薄膜光学常数与荧光光谱的研究

采用溶胶-凝胶工艺与原位生长技术，制备了ZnSe/SiO₂复合薄膜.X射线衍射分 析表明薄膜中ZnSe晶体呈立方闪锌矿结构.X射线荧光分析结果显示薄膜中Zn与Se摩尔比为1 ∶1.01—1∶1.19.利用场发射扫描电子显微镜观察了复合薄膜的表面形貌，结果表明复合薄 膜表面既存在尺寸约为400nm的ZnSe晶粒，也存在尺寸小于100nm的ZnSe晶粒.利用椭偏仪测 量了薄膜椭偏角Ψ，Δ与波长λ的关系，采用Maxwell-Garnett有效介质理论对薄膜的光学 常数、厚度、气孔率、ZnS 关键词： 2复合薄膜')" href="#">ZnSe/SiO₂复合薄膜 光学性质 椭偏光度法 荧光光谱     

Spectral and photochemical characteristics of CdSe nanoparticles stabilized in polymer-containing media

The optical characteristics of CdSe nanoparticles, produced in aqueous solutions and polymer films in the reaction of cadmium chloride and sodium selenosulfate, were studied. The main parameters that make it possible to vary the forbidden band width were identified. The absorption, photoluminescence, Raman, and nonstationary decolorization spectra of CdSe nanoparticles of various sizes were analyzed. It was demonstrated that under the conditions of pulsed irradiation the CdSe nanoparticles are capable of accumulating excess electrons and inducing redox transformations in components of the solution (oxygen, methylviologen, and sulfite ions). __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 3, pp. 150–155, May–June, 2006.     

CdSe纳米线阵列的制备及其表征(英)

通过在含有SeSO₃^2-和Cd²⁺的室温水溶液中，用模板-电沉积法在纳米孔阵列阳极氧化铝膜(AAM)模板中制备了高有序性的CdSe纳米线阵列，并对其形貌、结构和组分进行了表征。扫描电子显微镜(SEM)和透射电子显微镜(TEM)结果表明，纳米线阵列中的CdSe纳米线具有相同的长度和直径，分别对应于使用的AAM模板的厚度和孔径；X-射线衍射(XRD)和X-射线能谱(EDAX)结果表明，CdSe纳米线中Cd和Se的化学组成非常接近于1∶1，其结构为立方CdSe。另外，对模板-电沉积法制备CdSe纳米线的机理进行了讨论。     

Photocatalytic Synthesis of Composite CdSe/CdS Nanoparticles

We have shown that CdSe/CdS nanocomposites can be obtained in a photocatalytic reaction with participation of CdS nanoparticles from sodium selenosulfate. We have studied the kinetic characteristics of this process in detail and have shown that its most likely mechanism includes a step involving reaction between SeSO^3/2− anions and electrons generated in the conduction band of the CdS nanoparticles during irradiation and stabilized in traps on the semiconductor surface.__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 3, pp. 171–175, May–June, 2005.     

Photoelectrochemical behavior of coupled SnO2|CdSe nanocrystalline semiconductor films

A photoelectrochemical cell with a coupled SnO₂|CdSe nanocrystalline semiconductor electrode has been prepared by sequential deposition of SnO₂ and CdSe films onto an optically transparent electrode (OTE), and its photoelectrochemical behavior has been studied. The results show that the coupling of CdSe with SnO₂ leads to an improvement in the performance of OTE|SnO₂|CdSe over OTE|CdSe cells in terms of increased incident photon-to-current conversion efficiency, increased stability and smaller reversal of current. The favorable positioning of the energy bands of SnO₂ and CdSe is responsible for the above observations. Various photoelectrochemical parameters of the OTE|SnO₂|CdSe cell obtained for an incident light power of 0.31 mW cm⁻² at 470nm, are as follows: I_sc ≈ 25–30 μA cm⁻², V_oc ≈ 0.5–0.6 V, ƒƒ = 0.47 and a power conversion efficiency of about 2.25%.     

Preparation and characterization of high-specific-surface-area activated carbons from K2CO3-treated waste polyurethane

An activated carbon with high specific surface area was prepared from polyurethane foam by chemical activation with K2CO3 and the influences of carbonization temperature and impregnation ratio on the pore structure of the prepared activated carbon were investigated. It was found that the specific surface area of the activated carbon was at a maximum value (about 2800 m(2)/g) at a carbonization temperature of 1073 K and at an impregnation ratio of 1.0. It was concluded that the polyurethane foam structure was modified during impregnation by K2CO3, K2CO3 promoted charring during carbonization, and then the weight loss behavior was changed below 700 and above 1000 K, carbon in the char was consumed by K2CO3 reduction, and this led to the high specific surface area. The prepared activated carbon had a very sharp micropore size distribution, compared with the commercial activated carbon having high specific surface area. The amounts of three organic vapors (benzene, acetone, and octane) adsorbed on the prepared activated carbons was much larger than those on the traditional coconut shell AC and the same as those on the commercial activated carbon except for octane. We surmised that the high specific surface area was due to the modification of the carbonization behavior of polyurethane foam by K2CO3.     

发光反应型有机铵分子与CdSe纳米晶的组装

用巯基乙酸做稳定剂制备了水溶性CdSe纳米颗粒, 用十六烷基三甲基溴化铵(HTAB)、发光性(4-甲氧基均二苯乙烯基)二甲基乙基溴化铵 (MODAB)及末端含有双键的(4-甲基丙烯酰氧基均二苯乙烯基)二甲基乙基溴化铵(MSDAB)对该CdSe纳米颗粒进行了混合组装.通过改变三种有机分子的比例可以调控所得组装体的溶解性、聚合性及其发光性质.实验结果表明,当HTAB:MODAB:MSDAB=1:5.98～5.90:0.02～0.10(摩尔比)时,所得组装体具有较好的聚合性、溶解性和荧光性质.     

Monocrystalline ZnSe as an ionising radiation detector operated over a wide temperature range

This work presents an analysis of the main requirements for semiconductor detectors of ionising radiation that can be operated over a wide temperature range. The analysis shows that wide-gap semiconductors with a band gap greater than 2.0 eV are a better option for effective detection of ionising radiation at high temperatures. The results of an experimental investigation into the luminescent, electrical and spectrometric properties of the wide-gap semiconductor ZnSe are shown as an example. Undoped monocrystalline ZnSe has an extremely low leakage current over a wide range of temperatures up to 167 °C and can be used as a radiometric X-ray detector in pulse-counting mode over a wide temperature range up to at least 130 °C.