用拉曼散射光谱估算纳米Ge晶粒平均尺寸

用射频共溅射技术和真空退火方法制备了埋入ＳｉＯ２基底中的纳米Ｇｅ复合膜（ｎｃ－Ｇｅ／ＳｉＯ２）测量了不同温度退火后该复合膜的拉曼散射光谱，其结果与晶体Ｇｅ的拉曼谱相比，纳米Ｇｅ的拉曼峰红移峰形变宽，用拉曼谱的参数计算了纳米Ｇｅ晶粒的平均尺寸，所得结果与声子限域理论模型符合。     

溶胶—凝胶法制备CdS微晶掺杂TiO2／SiO2薄膜及其非线性光学特性

采用溶胶－凝胶方法在普通的载玻片上制备了ＣｄＳ微晶掺杂的ＴｉＯ２／ＳｉＯ２复合薄膜。用正硅酸乙酯、钛酸丁酯、醋酸镉作原料，比较了两种硫化剂：硫尿和硫代乙酰氨的硫化作用。Ｘ射线衍射谱和拉曼光谱揭示了ＣｄＳ微晶镶嵌在ＴｉＯ２／ＳｉＯ２薄膜的玻璃网络中。不同热处理温度、不同热处理时间的吸收光谱表明薄膜中存在着量子尺寸效应。采用Ｚ扫描技术测量了薄膜的非线性吸收及非线性折射率ｎ２＝－４．６７×１０－７ｅｓｕ。     

壳聚糖中ZnS：Mn纳米微晶的发光效率及时间分辨光谱

对制备的分散在壳聚糖中ＺｎＳ：Ｍｎ纳米微晶的红外吸收光谱，Ｘ射线衍射谱，激发和发射光谱，发光效率，时间分辨光谱进行了研究，讨论了发光性质变化的原因，实验表明，纳米微晶中Ｍｎ＾２＋的弛豫时间比体材料减少了约２个数量级，通过测量结果讨论了振子强度的变化。     

壳聚醣中ZnS: Mn纳米微晶的发光效率及时间分辨光谱

对制备的分散在壳聚醣中ＺｎＳＭｎ纳米微晶的红外吸收光谱、Ｘ射线衍射谱、激发和发射光谱、发光效率、时间分辨光谱进行了研究，讨论了发光性质变化的原因．实验表明，纳米微晶中Ｍｎ２＋的弛豫时间比体材料减少了约２个数量级．通过测量结果讨论了振子强度的变化     

含ZnS∶Mn~(2+)纳米晶玻璃中Mn~(2+)三种格位态的EPR研究

通过对ＺｎＳ∶Ｍｎ２＋ 不同含量的钠硼硅玻璃发光和激发光谱测量， 发现Ｍｎ 离子可能占据替位（Ｍｎ２＋ ）Ｓｕｂ 和间隙（Ｍｎ２＋ ）ｉｎｔ两种格位． 进一步的电子顺磁共振（Ｅｌｅｃｔｒｏｎ Ｐａｒａｍ ａｇｎｅｔｉｃＲｅｓｏｎａｎｃｅ， ＥＰＲ）实验证实了这一判断， 并从ＥＰＲ谱确认（Ｍｎ２＋ ）Ｓｕｂ， （Ｍｎ２＋ ）ｉｎｔ和Ｍｎ 团三种格位态的存在． 观测到ｇ 因子和超精细结构（ＨＦＳ）常数随纳米晶粒径的减小而增大． 这可能是由于量子限域效应下ＺｎＳ的ｓｐ３ 和Ｍｎ 的３ｄ５ 电子态杂化和表面态所引起的．     

纳米Ge颗粒镶嵌薄膜的Raman散射光谱研究

研究了镶嵌在ＳｉＯ_２介质中的不同尺寸（４—１６ｎｍ）纳米Ｇｅ颗粒的Ｒａｍａｎ散射谱特征，与大块标准Ｇｅ晶体的散射峰相比，观察到了理论预期的纳米半导体粒子的Ｒａｍａｎ散射峰的宽化和红移现象．采用声子限域模型较好地解释了实验结果．探讨了ＳｉＯ_２介质基体作用于镶嵌Ｇｅ粒子的压应力以及纳米Ｇｅ粒子的表面界面效应对Ｒａｍａｎ散射光谱的峰形、峰位变化所产生的影响 关键词：     

氨处理溶胶-凝胶SnO2薄膜的光学性质

采用溶胶－凝胶法制备ＳｎＯ２薄膜,通过对薄膜的不同处理方式（热处理和氨处理）所获得的ＳｎＯ２薄膜的比较,研究了氨处理ＳｎＯ２薄膜的光学性质。实验结果表明氨处理溶胶－凝胶ＳｎＯ２薄膜不仅具有良好的增透特性,同时也具有较好的机械强度和电学性能。     

纳米（Li2AO4）1—x—（ZrO2）x固体电解质陶瓷

用溶液凝胶共混法制备了纳米级的Ｌｉ２ＳＯ４－ＺｒＯ２复合固体电解质陶瓷。在复合陶瓷中，Ｌｉ２ＳＯ４、ＺｒＯ２的晶粒平均尺寸分别为４５、２７ｎｍ。晶粒尺寸的纳米化在材料中引入了大量的界面结构和表面结构。研究了掺不同量的纳米ＺｒＯ２第二相对Ｌｉ２ＳＯ４相变温度、相变行为及体系电导的影响，在纳米ＺｒＯ２作用下，Ｌｉ２ＳＯ４的相变温度可以降低１４０℃。在适当配比时，在５４０℃其离子电导可达到０．２Ｓ／ｃｍ     

表面包覆的SnO2纳米微粒的红外振动特征

测定了裸的和表面包覆有阴离子表面活性剂的ＳｎＯ２纳米微粒的红外吸收光谱。发现后者存在着一个随频率升高而增大的红外背景吸收带，其强烈影响材料的各振动模式的红外吸收强度，并对此现象进行了初步解释。     

纳米SnO_2的FT-IR研究

纳米ＳｎＯ２的ＦＴ┐ＩＲ研究张昊刘玉龙朱恪（中国科学院物理研究所北京１０００８０）熊永红熊曹水（中国科学技术大学基础物理中心合肥２３００２６）萧季驹（香港城市大学物理及材料科学系九龙香港）ＦＴ┐ＩＲＳｔｕｄｙｏｆＮａｎｏｍｅｔｅｒＳｎＯ２ＺｈａｎｇＨ...     

Oxygen vacancy density-dependent transformation from infrared to Raman active vibration mode in SnO2 nanostructures

Raman spectra acquired from spherical, cubic, and cuboid SnO2 nanocrystals (NCs) reveal a morphologically independent Raman mode at ～302?cm(-1). The frequency of this mode is slightly affected by the NC size, but the intensity increases obviously with decreasing NC size. By considering the dipole changes induced by oxygen vacancies and derivation based on the density functional theory and phonon confinement model, an oxygen vacancy density larger than 6% is shown to be responsible for the transformation of the IR to Raman active vibration mode, and the intensity enhancement is due to strong phonon confinement.     

Cooling dynamics of self‐assembled monolayer coating for integrated gold nanocrystals on a glass substrate

Picosecond time‐resolved X‐ray diffraction has been used to study the nanoscale thermal transportation dynamics of bare gold nanocrystals and thiol‐based self‐assembled monolayer (SAM)‐coated integrated gold nanocrystals on a SiO₂ glass substrate. A temporal lattice expansion of 0.30–0.33% was observed in the bare and SAM‐coated nanocrystals on the glass substrate; the thermal energy inside the gold nanocrystals was transported to the contacted substrate through the gold–SiO₂ interface. The interfacial thermal conductivity between the single‐layered gold nanocrystal film and the SiO₂ substrate is estimated to be 45 MW m^?2 K^?1 from the decay of the Au 111 peak shift, which was linearly dependent on the transient temperature. For the SAM‐coated gold nanocrystals, the thermal dissipation was faster than that of the bare gold nanocrystal film. The thermal flow from the nanocrystals to the SAM‐coated molecules promotes heat dissipation from the laser‐heated SAM‐coated gold nanocrystals. The thermal transportation of the laser‐heated SAM‐coated gold nanocrystal film was analyzed using the bidirectional thermal dissipation model.     

单分散性CdSe纳米晶的合成——成核及其生长过程

 在氩气保护下,用三辛基亚磷酸和油酸分别作为Se和Cd的配位体,在260～300 ℃的十八烯溶液中合成了尺寸可控的CdSe纳米晶。该纳米晶不用进行进一步的提纯和尺寸分离就具有单分散性,其量子尺寸限域效应非常明显——吸收光谱的第一吸收峰峰位随着纳米晶的长大而发生红移;该纳米晶质量很高,具有很强的发光能力,其发射光谱对称的形状和合理的Stokes频移（13 nm）显示,该纳米晶的发光完全出自带隙,没有来自缺陷的发光。此外,实验结果表明,通过改变三辛基亚磷酸的浓度可以调节成核和生长的快慢,从而可以在不同的反应时间得到不同尺寸的单分散性CdSe纳米晶。     

Optical diffuse reflectance spectra of GaSb nanocrystals embedded in SiO2 matrix by radio-frequency magnetron co-sputtering

Nanocrystalline GaSb embedded in SiO₂ films was grown by radio-frequency magnetron co-sputtering. X-ray diffraction pattern and transmission electron microscopy (TEM) confirm the existence of GaSb nanocrystals in the SiO₂ matrix. The average size of GaSb nanoparticles is in the range of 3 to 11 nm. Diffuse reflectance spectra were used to characterize the small change of the band gap of the semiconductor. The diffuse reflectance spectra shows that the absorption peaks have a large blueshift of about 4.0 eV of the absorption relative to that of bulk GaSb. It has been explained by quantum confinement effects. Room temperature optical transmission spectra show that the absorption edge exhibits a very large blueshift of about 2.1 eV with respect to that of bulk GaSb in agreement with quantum confinement. Received: 28 July 1999 / Accepted: 27 October 1999 / Published online: 1 March 2000     

Nano-confined and copper-defect in wide-bandgap semiconductors

Copper-doped cadmium iodide nanocrystals were synthesized and grown for an investigation of the optical nonlinear effects via the measurements of the second harmonic generation (SHG) and nonlinear transmittance (NLT). The second-order optical susceptibilities in dependences of the size of the nanocrystals as well as of their copper contents were calculated. The observed size dependence demonstrates the nanosized quantum-confined effect, where the quantum confinement dominates the material's electronic and optical properties, with a clear increase in the SHG with decreasing the thickness of the nanocrystals. A dramatic change of the second-order optical response with increasing copper content of the nanocrystals was also observed. Optical absorption of the nanocrystals studied using NLT technique shows a decrease of the two-photon absorption with increasing thickness of the nanocrystals. The obtained results are discussed in details by exploring the photo-induced electron-phonon anharmonic mechanism for noncentrosymmetry of the impure material processes involving quantization.     

Photoluminescence quenching of CdTe/CdS core-shell quantum dots in aqueous solution by ZnO nanocrystals

Photoluminescence (PL) properties of 3-mercaptopropionic acid (MPA) coated CdTe/CdS core-shell quantum dots (QDs) in aqueous solution in the presence of ZnO colloidal nanocrystals were studied by steady-state and time-resolved PL spectroscopy. The PL quenching of CdTe/CdS core-shell QDs with addition of purified ZnO nanocrystals resulted in a decrease in PL lifetime and a small red shift of the PL band. It was found that CdTe(1.5 nm)/CdS type II core-shell QDs exhibited higher efficiency of PL quenching than the CdTe(3.0 nm)/CdS type I core-shell QDs, indicating an electron transfer process from CdTe/CdS core-shell QDs to ZnO nanocrystals. The experimental results indicated that the efficient electron transfer process from CdTe/CdS core-shell QDs to ZnO nanocrystals could be controlled by changing the CdTe core size on the basis of the quantum confinement effect.     

CdSe/CdS核/壳型纳米晶的光谱特性

以巯基乙酸为稳定剂制备了CdSe/CdS核／壳型纳米晶。用光吸收谱（Abs)、光致发光谱（PL）及光致发光激发谱（PLE）研究了CdS壳层对CdSe纳米晶电子结构，从而对其吸收和发光性能的影响。根据PL和PLE的结果以及带边激子精细结构的计算结果，我们用尺寸很小的纳米晶中所形成的基激缔合物解释了PL光谱与吸收边之间较大的Stokes位移。     

GaAs/SiO2纳米晶镶嵌薄膜的拉曼光谱与吸收光谱研究

采用射频磁控共溅射与高真空退火相结合的方法,分别在单晶硅片和光学石英玻璃片上制备了ＧａＡｓ／ＳｉＯ２纳米晶镶嵌薄膜样品。激光拉曼光谱的测量结果表明,退火态样品（４００℃,６０ｍｉｎ）的拉曼光谱特征峰呈现宽化和红移,红移量为９．５ｃｍ＾－１,对应薄膜中ＧａＡｓ纳米晶粒平均粒径约为３ｎｍ。样品的室浊吸收光谱测量结果表明,由于受量子限域效应的主导作用,与ＧａＡｓ块状单晶相比,样品光学吸收边呈现出明显的蓝