纳米磷化镓粉体还原氮过程的Raman光谱分析

利用Raman光谱对还原氮后的纳米磷化镓(GaP)粉体进行了表征。结果表明:纳米GaP粉体表面含有Ga-O,P-O和H-O化学键。此外,进行氮还原过程后,在Raman位移约为1700~3300cm-1范围内(相当于709~800nm或1.55~1.75eV),纳米GaP的Raman光谱出现了一个宽、强荧光发射峰;而在未进行通氮处理的纳米GaPRaman光谱中,没有观察到该荧光峰的存在。本文对该荧光发射峰的起因作了初步分析。     

纳米磷化镓粉体中混杂石墨和金刚石微晶的拉曼光谱分析

利用Raman光谱并结合能量色散X射线显微分析(EDX)和X射线衍射图谱(XRD)对混杂于纳米磷化镓粉体内的石墨和金刚石纳米微晶进行了分析。结果表明,在纳米GaP粉体Raman光谱中,位于1324 cm-1和1572 cm-1的两个宽强散射谱带分别归属于金刚石的F2g模和石墨的E2g模振动。EDX结果证实纳米GaP粉体材料中含有碳元素。XRD图谱中出现了石墨和金刚石的低晶面指数衍射峰。     

结晶紫在纳米磷化镓粉体表面吸附的表面增强拉曼光谱分析

利用Raman光谱对结晶紫(Crystal Violet,CV)在纳米磷化镓(GaP)粉体表面的吸附状态进行了分析.结果表明:与普通拉曼散射谱(Normal Raman Scattering,NRS)相比,结晶紫表面增强拉曼散射(Surface Enhanced Raman Scattering,SERS)谱的4种振动模式,即:中央键的呼吸振动、环-C -环面外弯曲振动、环C-H面外弯曲振动以及N-环伸缩振动,在纳米GaP粉体表面得到增强;通过分析吸附前后结晶紫拉曼散射峰相对强度的变化,确定了结晶紫在纳米GaP粉体表面的吸附取向,并对其表面增强散射机理进行了探讨.     

a-C:N:H纳米尖端荧光产生的机理

用CH4,H2和NH3为反应气体,利用等离子体增强热丝化学气相沉积在沉积有碳膜的Si衬底上制备了a-C:N:H纳米尖端,并用扫描电子显微镜和微区Raman光谱仪对碳膜和纳米尖端进行了表征。结果表明:Raman谱中含有与碳和氮相关的峰,且纳米尖端的Raman谱比碳膜的Raman谱有很强的荧光背景。Raman谱中的峰说明沉积的碳膜和纳米尖端是a-C:N:H薄膜和a-C:N:H尖端。a-C:N:H纳米尖端的Raman谱中强荧光背景的产生表明其在激发光源照射的过程中发射了强荧光,对a-C:N:H纳米尖端产生强荧光的机理进行了探讨。     

炸药爆轰法制备的纳米石墨粉的拉曼光谱

负氧平衡炸药爆轰法合成的纳米石墨粉,是一种新型的具有良好实用前景的纳米粉体材料。采用负氧平衡炸药梯恩梯(TNT),在分别充有氮气、氩气、二氧化碳等保护性气体、压力为0.25～2 atm的密闭容器内爆轰制备了纳米石墨粉。用激光拉曼光谱对制备的样品进行了测试,结果表明样品为石墨结构。纳米石墨粉的Raman峰与块体石墨相比,其峰位向高波数方向偏移了约5 cm-1。纳米石墨粉Raman峰的半高宽约为22 cm-1,由此可计算出纳米石墨粉的颗粒大小为2.97～3.97 nm。与高纯石墨Raman峰相比,纳米石墨粉的Raman峰由于尺寸效应出现了蓝移现象, 并对此现象进行了讨论。用X射线衍射仪(XRD)和透射电子显微镜(TEM)测定了纳米石墨粉的物相,并对其颗粒粒径进行了估算,其结果为2.58 nm(酸处理前)和1.86 nm(酸处理后),与Raman光谱的结果基本吻合。     

LPE碲镉汞薄膜的显微Raman谱与显微荧光谱分析

利用Raman显微镜系统对4块用液相外延(LPE)方法在Cd0.96Zn0.04Te衬底上生长的Hg0.8Cd0.2Te外延薄膜样品，在100～5 000cm^-1光谱范围进行测量，在实验曲线中除了观察到与碲镉汞材料晶格振动相符的类．HgTe的光学振动横模(TO1模)和纵模(LO1模)的Raman散射峰、类-CdTe光学振动横模(TO2模)和纵模(LO2模)混合的Raman散射峰以及来源于TO1 LO1的二级Raman散射峰外，在1 000～5 000cm^-1光谱范围首次发现了LPE碲镉汞薄膜的显微荧光峰，该显微荧光的发光范围换算为电子伏特标度为1．34～1．83eV．发光中心位于2750cm^-1即1.62eV，发光峰的半高宽(FWFIM)约为0．25eV。通过分析指出．该显微荧光来源于碲镉汞外延层中阴性离子空位与材料导带底的共振能级的发光。     

掺铋离子BaO-B203玻璃的制备及其近红外发光性能的研究

采用高温熔融法制备了掺Bi离子的BaO—B203玻璃,测定了样品玻璃的近红外以及可见光区的激发、发射谱、荧光衰减曲线以及Raman光谱．在808nm波长光的激发下,在掺Bi离子的BaO—B203玻璃中发现了近红外发光现象．且存在多个发光峰．讨论了玻璃网络结构对Bi离子发光的影响,对其发光机理进行了初步的探讨．     

纳米GaP材料Ga填隙缺陷的EPR实验观察

利用电子顺磁共振(EPR)技术对纳米GaP粉体材料的本征点缺陷进行了研究，结果表明：由EPR信息的g因子值（2.0027±0.0004）可以确定纳米GaP粉体材料存在Ga自填隙（Ga_i）本征缺陷；纳米GaP粉体EPR信号超精细结构消失，以及谱线线宽（ΔH_PP）变窄等实验现象，可能是由纳米材料界面的无序性，以及缺陷原子和界面原子之间的电子交换造成的；在较低的测试温度范围内，升高温度引起纳米GaP材料发生晶界结构弛豫；当测试温度由100 K升高至423 K时，ΔH_PP值和自由基浓度皆逐渐降低.     

聚合物前驱体衍生SiC纳米棒的光学性质

采用聚硅氮烷前驱体热裂解方法制备SiC纳米棒,并利用SEM、XRD和EDX表征了SiC纳米棒的结构和组成,表明得到的SiC的组分比C：Si接近1：1。用微区Raman和光致发光方法研究了纳米棒的光学性质。观测到SiC的TO模式对应的Raman峰和相邻肩峰。对SiC纳米棒观测到其紫外3．25eV附近强的光致发光峰,我们认为它归结为α型SiC带间的跃迁。通过XRD、Raman和光发射谱,我们推测前驱体热裂解得到的SiC纳米棒是一个混晶,纳米棒的表层是立方晶,而内层主要为a—SiC。     

CdSe/CdS核壳纳米晶微波水热法一步合成与发光光谱分析

采用微波水热法一步合成了核壳结构的CdSe/CdS纳米晶,讨论了巯基丙酸中S^2-的释放过程对纳米晶生长的影响。XRD和Raman光谱结果表明,140℃合成温度下获得了CdSe/CdS核壳结构的纳米晶。FTIR光谱结果表明,巯基丙酸随时间的分解有助于CdS壳层的形成。PL光谱呈现出CdSe纳米晶的带间发射和缺陷发射,随着核壳结构的形成,CdSe纳米晶的表面缺陷被抑制,相关的荧光发射减弱。     

吸附于纳米磷化镓粉体表面碱性品红的拉曼光谱(英文)

本文中,对吸附于纳米磷化镓(GaP)粉体表面的碱性品红拉曼光谱进行了研究。通过将吸附碱性品红与纯碱性品红晶体样品的拉曼光谱进行对比、分析可知,碱性品红在纳米GaP粉体表面发生了化学吸附。在吸附碱性品红样品的拉曼光谱中,位于1200~1320cm-1范围内的光谱特征表明可能有新的化学键(P-O-C+或Ga-O-C+)形成。碱性品红分子的中央碳正离子(C+)与GaP表面具有孤对电子的氧原子形成配位键。红外光谱结果表明,氧原子与纳米GaP粉体表面的磷原子或镓原子键合,以P-O,Ga-O或P-O-Ga形式存在于GaP表面。碱性品红分子的呼吸振动,N-苯环伸缩振动,以及苯环C-C伸缩振动散射强度与纯碱性品红晶体样品相比皆有所增强。N-苯环伸缩振动散射强度增加意味着N原子是除C+离子以外的另一个可以与GaP表面发生化学作用的活性中心,这种化学作用是由N原子与GaP表面存在共轭效应造成的。     

Raman scattering from GaP nanowires

A complete Raman study of GaP nanowires is presented. By comparison with the Raman spectra of GaP bulk material, microcrystals and nanoparticles, we give evidence that the Raman spectrum is affected by the one-dimensional shape of the nanowires. The Raman spectrum is sensitive to the polarization of the laser light. A specific shape of the overtones located between 600 and 800 cm^-1 is actually a signature of the nanowires. Some phonon confinement and thermal behavior is also observed for nanowires.     

纳米GaP粉体对结晶紫的光催化降解及其振动光谱分析

对纳米 Ga P粉体 -结晶紫水溶液光催化降解进行了研究。纳米 Ga P粉体在紫外光照射条件下对结晶紫具有光催化降解作用 ;随平均颗粒度的降低 ,纳米 Ga P粉体的光催化活性增加。红外光谱测试结果表明 :进行光催化过程以后 ,纳米 Ga P表面存在的几种主要振动模式变化较小或不变 ;拉曼光谱测试结果表明 :纳米 Ga P粉体的横向光学声子模与纵向光学声子模 ,以及表面主要振动模式几乎没有发生变化     

碱性品红分子在纳米磷化镓粒子表面的吸附取向(英文)

利用表面增强拉曼光谱,初步确定了吸附于纳米磷化镓(GaP)粉体表面的碱性品红分子的取向。在295K时,将50 mg GaP粉体分别置于50 ml,4.7×10-3M和50 ml,4.74×10-6M碱性品红水溶液中。对由较高浓度溶液形成的吸附系统持续搅拌24小时;而对极稀溶液吸附系统则连续搅拌处理7天。在经过过滤、干燥处理后,吸附有染料分子的GaP粉体被直接用于碱性品红的表面拉曼光谱测试。通过对染料分子中央碳原子呼吸振动和氮-苯环伸缩振动模式的相对强度进行分析可知:在较高浓度的溶液中,染料分子主要以一种混合取向方式吸附于GaP粉体表面上,即“端基接触”和“平躺”两种方式;而在极稀溶液中,染料分子则仅以“端基接触”方式吸附于GaP粉体表面上。     

Raman scattering from surface optical phonon mode in gallium phosphide nanomaterials

The Raman scattering from gallium phosphide (GaP) nanoparticles (~53 nm) and nanosolids has been investigated. By means of Lorentzian fitting of the Raman scattering spectra, a surface optical phonon (SO) peak located between the transverse optical (TO) phonon and longitudinal optical (LO) phonon frequencies became observable. It has been proved by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) that a core-shell heterostructure is characteristic of the structure of GaP nanoparticles. According to electromagnetic theory, the SO frequency of the piezoelectric/semiconductor heterostructural nanomaterials was calculated.     

Amorphous-like Raman spectra of GaP microcrystals

Raman scattering from gas-evaporated GaP microcrystals smaller than about 400 Å has been investigated. As the crystalline size decreases from ～400 to ～170 Å, drastic changes in the Raman spectrum are observed; the TO and surface phonon peaks broaden and shift, and they strongly overlap with each other, finally transforming into a broad structure; broad bands located at around 80 and 200 cm^-1 appear and grow rapidly. The microcrystals smaller than about 250 Å show spectra very similar to those of amorphous GaP, even though the electron diffraction patterns prove that they are crystalline. The amorphous-like Raman signals seem to come from the surface layers of the microcrystals.     

Surface mode absorption and infrared optical properties of gallium phosphide nanoparticles

The surface optical (SO) mode of ellipsoidal gallium phosphide (GaP) nanoparticles is investigated by infrared transmission spectroscopy. The surface mode theory of diatomic cubic particles is generalized and applied to GaP nanoparticles in a systematic treatment. The Fröhlich mode of GaP nanoparticles has been observed in our experiment. As far as surface mode frequency is concerned, the result of the experiment agrees with that of the theoretical calculation. The characteristics of the SO mode peak, including frequency shift, broadening and line shape, are analyzed. The frequency shift is attributed to the surrounding medium effect, surface oxidation and the aggregation effect as well as intrinsic point defects; the broadening is mainly due to the non-spherical particle shape, aggregation and quantum confinement effect; and the line shape is related to the particle shape and the damping function.     

Raman of indigo on a silver surface. Raman and theoretical characterization of indigo deposited on silicon dioxide-coated and uncoated silver nanoparticles

Raman, surface-enhanced Raman scattering, and shell isolated nanoparticles-enhanced Raman scattering techniques were used to study the indigo–nanoparticle interaction nature. Silver nanoparticles were employed with and without a silicon dioxide spacer inert layer. The SERS spectral profile, obtained using silver nanoparticles, is different from the Raman one, which led to the proposition that the indigo–silver interaction is in the range of intermolecular interactions. SERS spectral reproducibility suggests identical organization and orientation of the analyte on the metal surface. The shell isolated nanoparticles enhanced Raman scattering spectrum of indigo, obtained by using silicon dioxide coated silver nanoparticles resulted similar to its Raman spectrum. This result indicates that the indigo structure is chemically unmodified by the silicon dioxide-coated silver surface. From the shell-isolated nanoparticles-enhanced Raman scattering experiments, the electromagnetic mechanism is proposed as the reason for the spectral enhancement. Theoretical calculations allow one to infer both the indigo–silver surface interaction nature and the orientation of indigo on the surface.