不同晶粒尺寸SnO2纳米粒子的拉曼光谱研究

对晶粒尺寸在4—80nm范围的纯SnO₂纳米颗粒进行了拉曼散射研究.除了SnO₂本征拉曼振动峰外，还有几个新的拉曼振动峰和波长在700nm左右的一个发光很强而且峰宽很大的荧光峰被观察到.结果所示，当纳米颗粒尺寸减小时，纳米SnO₂颗粒的体相 特征拉曼峰变弱，而由缺陷，表面和颗粒尺寸引起的相关效应呈强势.晶粒尺寸在20nm左右是引起体相拉曼光谱变化的临界尺寸.晶粒尺寸在20nm以下，其体相拉曼峰的发生宽化和峰位移动，以及分别出现在位于571cm^-1 的表面振动峰，位于351cm-1 处的界面峰和与表面吸附水分子及氢氧基团的N系列拉曼峰是纳米SnO颗粒的主要特征.这些结果反映了纳米颗粒的微结构变化与颗粒尺寸和表面效应以及它们之间相互作用的信息. 关键词： ２')" href="#">纳米SnO_２ 拉曼光谱 荧光光谱 水分子的吸附     

口红的荧光和拉曼光谱特性的研究

人们消费方式的变化促使电商崛起,美妆市场呈爆发式增长,口红产品的安全成为关注焦点。面对品牌口红真伪问题,市场检测化妆品方法单一,对品牌口红的特征无针对性。采用三维荧光技术和共聚焦拉曼技术对某品牌真假口红的光谱性质进行了研究。三维荧光光谱显示五组口红均存在激发光峰值波长为320 nm左右,发射峰波长在372 nm附近的荧光（Ⅰ区）。A1,A2,A3,B1,B2和B3这6个样品中,激发光峰值波长为230 nm时会发出中心波长在400 nm左右的荧光,而在A4,A5,B4和B5这4个样品中,激发光峰值波长红移到250 nm左右,其荧光发射峰也发生了相应的红移,到450~470 nm（Ⅱ区）。此外,A5还存在激发光峰值波长550 nm,发射峰在590 nm附近的荧光;B1还存在270 nm激发,292 nm左右发射的荧光峰（Ⅲ区）。采用荧光强度相对法来定量分析,若都以Ⅰ区的荧光强度为1,口红不同色号间、同色号真假口红间的Ⅱ区和Ⅲ区的相对荧光强度显著不同。拉曼光谱显示正品口红中存在TiO₂的振动峰,也还存在大量的C-C,C-N,-CH₂和-NH₂等有机化官能团的振动特征峰。相比于正品口红,部分假口红中还存在四个特异性的振动峰,分别是228,447,609和1 090 cm-1,这与Fe₂O₃的拉曼峰位吻合。实验结果表明口红不同色号间、同色号真假口红之间均存在着明显的光谱差异,利用口红光谱的指纹特性可实现对真假口红的鉴别。     

SnO$lt;sub$gt;2$lt;/sub$gt;纳米晶体的制备、结构与发光性质

使用软化学方法在碱性溶液中制备出了颗粒尺寸分布均匀的SnO₂纳米颗粒,使用透射电子显微镜（TEM）、X射线衍射（XRD）、光致发光谱（PL）和光吸收谱等方法分析与表征了SnO₂纳米颗粒的结构和光学性能.实验中通过表面活性剂的加入来控制纳米颗粒的结晶与凝聚.XRD,TEM的结果表明,原始制备出的SnO₂纳米颗粒的平均粒径小于4 nm,为完好的晶体状态.纳米颗粒经过400—1000 ℃退火后晶粒尺寸进一步增大.光吸收谱表明,相对于体材料,纳米颗粒的禁带宽度展宽并随颗粒尺寸增大而红移.光致发光谱测试表明,不同温度下退火的SnO₂纳米颗粒在350—750 nm有较强的发光,研究表明这是来源于颗粒表面的氧空位缺陷发光. 关键词： 氧化锡 表面活性剂 纳米颗粒 光致发光     

尺寸效应对Er3+掺杂纳米Y2O3的发光特性的影响

采用燃烧法制备了不同尺寸的Er³⁺掺杂Y₂O₃粉体材料,研究了尺寸效应对Er³⁺掺杂纳米Y₂O₃材料发光特性的影响.光声光谱显示,对于不同晶粒尺寸的样品,Er³⁺离子光声峰位置几乎保持不变.这表明小尺寸效应对稀土离子能级位置影响很小.对488nm激光激发下的发射谱的分析发现,随着样品颗粒尺寸的减小,4S_3/2能级和关键词： 3+离子')" href="#">Er³⁺离子 纳米 发光 能量传递     

蓝宝石基底上制备蠕虫状ZnO及强紫外发光性能研究

选用纳米球刻蚀技术在蓝宝石（Al₂O₃）基底上制备350 nm聚苯乙烯（PS）微球密排掩模版,然后采用反应射频磁控溅射方法分别在PS/Al₂O₃和Al₂O₃基底上沉积氧化锌（ZnO）薄膜,去除掩模版的PS微球后,对经退火处理的两种样品进行X射线衍射分析、扫描电子显微镜观察和荧光光谱测试。结果表明,在PS/Al₂O₃上生长的ZnO薄膜（样品1）的晶粒呈明显的蠕虫状,而直接在Al₂O₃基底上生长的ZnO薄膜（样品2）表面晶粒为不完全六棱台形状。样品2的结晶性能优于样品1,但是在362 nm附近样品1的近带边缘荧光发射峰强度比样品2的发射峰强43倍。     

Al3+对Ge/Al-SiO2薄膜光致发光的影响

采用磁控溅射及后退火技术制备了不同组份和不同退火温度的Ge、Al共掺SiO₂薄膜。通过对样品的X射线光电子能谱(XPS)测试,确定了薄膜的成分和结构特征;同时还测试了样品的光致发光谱(PL谱),得到了峰值位于420 nm附近的紫光发射峰和峰值位于470 nm的蓝光发射峰。实验结果表明, Al的掺杂不仅可以显著地提高GeNOV中心和SiNOV中心的光发射效率,还可以促进GeNOV缺陷和SiNOV缺陷中心的形成,进而有利于薄膜的光致发光。     

Au/SiO2纳米多层薄膜的制备及其性质表征

利用多靶磁控溅射技术制备了Au/SiO₂纳米颗粒分散氧化物多层复合薄膜.研究了在保持Au单层颗粒膜沉积时间一定时薄膜厚度一定、变化SiO₂的沉积时间及SiO₂的沉积时间一定而改变薄膜厚度时，多层薄膜在薄膜厚度方向的微观结构对吸收光谱的影响.研究结果表明：具有纳米层状结构的Au/SiO₂多层薄膜在560 nm波长附近有明显的表面等离子共振吸收峰，吸收峰的强度随Au颗粒的浓度增加而增强，在Au颗粒浓度相同的情况下，复合薄膜 关键词： 2纳米复合薄膜')" href="#">Au/SiO₂纳米复合薄膜 多靶磁控溅射 吸收光谱 有效介质理论     

金纳米粒子掺杂DNA-CTMA-DPFP薄膜的表面增强拉曼散射特性

采用柠檬酸三钠还原氯金酸和离子交换法制备金纳米粒子掺杂DNA-CTMA材料,利用钯催化反应合成9,9-二乙基-2,7-二-(4-吡啶)芴荧光染料(DPFP),将DPFP与DNA-CTMA混合后,旋凃制备金纳米粒子掺杂的DNA-CTMA-DPFP薄膜样品。通过吸收光谱、荧光光谱和拉曼光谱的测量,研究了薄膜样品的光学特性和表面增强拉曼散射(SERS)特性。实验结果表明,薄膜样品在300～360 nm的吸收主要来自DPFP,在500～700 nm的吸收来自样品中金纳米粒子的局域表面等离子共振;样品在370,386,408 nm处的荧光峰分别对应DPFP的S₁₀-S₀₀、S₁₀-S₀₁和S₁₀-S₀₂能级的电子振动跃迁;在785 nm激光激发下,薄膜样品的拉曼散射主要来自DPFP分子,随着金纳米粒子掺杂比的增大,DPFP分子的拉曼散射峰强度逐渐增强。因此,金纳米粒子掺杂DNA-CTMA薄膜适合作为多种染料分子的SERS基底。     

通过飞秒泵浦探测技术研究PbS纳米颗粒的激发态瞬态动力学过程

利用飞秒泵浦探测技术研究了PbS半导体纳米颗粒复合的SiO₂溶胶凝胶薄膜的瞬态动力学过程。通过改变激发探测波长和激发光强度,研究引起PbS半导体纳米颗粒的非线性吸收的两种机制。当激发探测波长选在激子吸收峰附近(620nm)时,由于激子的饱和吸收引起的光致漂白,当激发波长选在激子能态的低能侧(753,800nm),同时观察到激子的饱和吸收和双激子效应引起的光致吸收。研究了激子的饱和吸收和双激子效应引起的激发态吸收随激发态电子-空穴对浓度的变化关系,表明双激子效应与载流子浓度有很大关系。在高激发强度下,双激子效应引起的诱导吸收远远大于激子跃迁引起的光致漂白,双激子效应在非线性吸收中起着决定性作用。     

退火及超声处理对ZnO薄膜结构和发光特性的影响

 利用对向靶射频磁控溅射系统在Si（100）衬底上制备了ZnO薄膜，并对其进行了退火和超声处理。采用XRD,AFM和光致发光谱对其结构、表面形貌和性能进行了分析。结果表明：沉积态ZnO薄膜（002）择优取向稍差,尺寸较小,表面粗糙度较大。随退火温度的升高，颗粒粒径增大，样品的取向性和结晶度都明显变好，应力状态由压应力转变为张应力,粗糙度降低。超声处理缓解了薄膜中的张应力，晶粒尺寸更趋增大;用波长为280 nm的激发光激发薄膜时，沉积态薄膜无发光峰存在;随着退火温度升高，出现了一个378 nm的紫外峰和一个398 nm的紫峰;紫外峰峰值强度随退火温度升高不断增强，而紫峰的峰位随退火温度升高基本不发生变化，峰值强度增强;700 ℃退火后的薄膜经超声处理后，发光谱中出现了峰值波长为519 nm的绿色发光带。     

Volume of precursor solution effect on the properties of SnO<Subscript>2</Subscript> thin films prepared by nebulized spray pyrolysis technique

Undoped SnO₂ thin films have been deposited on amorphous glass substrates with different precursor solution volume (10, 15, 20 and 25 ml) using simple and cost-effective nebulized spray pyrolysis technique. The influence of precursor solution on structural, optical, photoluminescence and electrical properties had been studied. The X-ray diffraction spectra prove the polycrystalline nature of SnO₂ with tetragonal structure. All the films show a preferred growth orientation along (110) diffraction plane. The average transmittance of SnO₂ thin films varied between 82 and 75% in the visible as well as IR region. The band gap energy decreases from 3.74 to 3.64 eV corresponding to direct transitions with the precursor solution volume had increased from 10 to 20 ml and then increased as 3.72 eV for 25 ml. SEM pictures demonstrated polyhedrons like grains. EDX confirmed the existence of Sn and O elements in all the prepared SnO₂ thin films. Photoluminescence spectra at room temperature revealed that the four emission bands in all the samples such as sharp dominant peak at 361 nm with shoulder peak at 377 nm (UV region), a broad and low intensity peak at 492 nm (blue region) and 519 nm (green region). The electrical parameters were examined by Hall effect measurements, which demonstrated that the film prepared at 20 ml precursor solution volume possess minimum resistivity 2.76?×?10^?3 Ω-cm with activation energy 0.10 eV and maximum figure of merit 1.54?×?10^?2 (Ω/sq)^?1.     

钛酸锶钡薄膜的室温光学性能研究

采用溶胶-凝胶法制备了(Ba0.75Sr0.25)TiO3薄膜,研究了不同退火温度下样品的物相结构、薄膜的光致发光性能和光学透过率。结果表明:室温下非晶钛酸锶钡薄膜在蓝光激发下具有明显的发光现象,发光波长范围是500～650 nm,峰值在525 nm附近。延长非晶态薄膜的退火时间能够显著提高样品的发光强度,且发光强度随薄膜厚度增加而增大。晶态薄膜有微弱的发光现象。透射谱测试结果表明,钛酸锶钡薄膜在可见光范围内具有良好的光学透过率。     

Structural and photoluminescent properties of TiN thin films

Structural and photoluminescent properties of TiN thin films deposited by dc reactive magnetron sputtering are studied. It is found that TiN thin films are polycrystalline with a grain size of ～15 nm and have a NaCl-type cubic crystal structure with a lattice constant of 0.42 nm. The TiN films under study exhibit photoluminescence in the spectral range h _ν ≈ 2.1–3.4 eV at 300 K.     

Synthesis and characterization of ZnO nano/microfibers thin films by catalyst free solution route

Zinc oxide (ZnO) nano/microfibrous thin films were successfully synthesized by a catalyst free solution route on glass and Si substrates. X-ray diffraction study revealed the formation of ZnO nanofibers of hexagonal crystalline structure. The texture coefficient of different planes varied with annealing temperature and that of the (0 0 2) plane was the highest for films annealed at temperature 873 K. Scanning electron micrograph showed the well formation of ZnO nano/microfibers with an average diameter 500 nm and having an average aspect ratio 150. UV–Vis–NIR spectroscopic study for the films deposited on glass substrates showed the high transmittance in the visible and near-infrared region. It was also observed that the band gap energy decreased as the films were annealed at higher temperature. The band gap energies of nanostructured ZnO thin films were determined to be in the range 3.03–3.61 eV. The photoluminescence study showed an UV emission peak at 397 nm, a visible blue–green emission peak at 468 nm and a green emission peak at 495 nm. Field emission properties of nanofiber ZnO thin film showed considerably low turn-on field around 1.4 V/μm. The emission current was as high as 70 μA at the field of 3.6 V/μm.     

Photophysical processes stimulated in nanoporous silicon by high-power laser radiation

Photoprocesses initiated on the surface of porous silicon irradiated with laser radiation with wavelengths (λ = 266, 337, and 532 nm) in a wide range of intensities (up to 2 × 10⁷W/cm²) were investigated. Laser-induced luminescence and laser mass-spectrometry were used as experimental procedures. X-ray reflection was used to determine the parameters of the porous silicon films. The photoluminescence spectra obtained at different wavelengths and low intensities were analyzed. This analysis showed that for an optically thin layer of porous silicon the luminescence spectrum does not depend on the wavelength of the exciting radiation. This indicates the existence of a separate system of levels in porous silicon that are responsible for the luminescence. The behavior of the photoluminescence spectra as a function of the intensity q of the exciting radiation was investigated. It was shown that the luminescence intensity is a nonlinear function of q. At high intensities of the exciting radiation, the luminescence intensity saturates and a short-wavelength shift of the spectra is observed; this is due to the high concentrations of photoexcited carriers. This increases the probability of the experimentally observed nonequilibrium photodesorption of H₂ and Si from the surface of porous silicon.     

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：     

Room temperature photoluminescence property of Mo-doped In2O3 thin films

Mo-doped In₂O₃ thin films have been prepared on glass substrates using an activated reactive evaporation method and systematically studied the effect of oxygen partial pressure on the structural, optical, electrical and photoluminescence properties of the films. The obtained films are highly transparent and conductive. The films exhibited the lowest electrical resistivity of 5.2 × 10⁻⁴ Ω cm, with an average optical transmittance of 90% in the visible region. An intensive photoluminescence emission peaks were observed at 415 and 440 nm.     

Luminescence properties from erbium oxide nanocrystals dispersed in titania/organically modified silane composite sol–gel thin films

Luminescence properties from erbium (III) oxide nanocrystals dispersed in titania/organically modified silane composite thin films were studied. Erbium oxide nanocrystals were prepared by an inverse microemulsion technique. A strong room-temperature photoluminescence was observed at 1.531 μm, with the full width at half maximum (FWHM) of 22 nm due to intra-atomic transitions between ⁴ I _13/2 and ⁴ I _15/2 levels in the erbium (III) ion. The shape, peak position, and FWHM of the photoluminescence signals from the composite thin films were quite comparable to those prepared by other methods. The photoluminescence peak of the composite thin films showed a maximum intensity at the heat-treatment temperature of 300 °C. A room-temperature green up-conversion emission at 543 nm (⁴ S _3/2?⁴ I _15/2) was observed for the composite thin films with different heat-treatment temperatures upon excitation at 993 nm. The up-conversion emission mechanism was explained by means of an energy-level diagram and the lifetime of the visible up-conversion emission was measured. Received: 10 July 2000 / Accepted: 11 July 2000 / Published online: 5 October 2000     

CCD紫外敏感Lumogen薄膜制备与光谱表征

传统的CCD和CMOS成像传感器对紫外区域响应比较弱,这是因为多晶硅栅对紫外光有强的吸收能力,从而阻碍了紫外光进入CCD沟道。为了提高探测器对紫外辐射的敏感性,可行的一种办法是在器件上镀一层可以将紫外光转化为可见光的变频膜。采用真空蒸发法制备了有机Lumogen薄膜,并用发光官能团分析、椭圆偏振技术研究了Lumogen薄膜的发光原理与光学常数。分析与实验结果表明：Lumogen可连续光致发光原因是其分子具有四类双键结构;椭圆偏振法测得该Lumogen薄膜折射率在1.3左右,说明该膜具有增透效果。同时,通过测量Lumogen薄膜的透射光谱、吸收光谱、光致发光发射谱和激发谱,表征了Lumogen薄膜的光谱性质,发现Lumogen薄膜在可见波段(>470 nm)有较好的透过性,用紫外光激发会产生较强的黄绿光(中心波长位于523 nm),且激发光谱宽(240～490 nm)。结论表明Lumogen薄膜的发射光谱能够与CCD等传统硅基成像器件的响应光谱匹配,是一种符合实际要求的紫外敏感薄膜。     

Structural and optical properties of ZnO thin films on (111) CaF2 substrates grown by magnetron sputtering

ZnO thin films were grown on (111) CaF₂ substrates by magnetron sputtering at room temperature. Structural and optical properties of the ZnO thin films were studied. XRD analysis showed that the ZnO thin films had the (002) preferential orientation. The transmittance of ZnO thin films was over 80% in the visible range. The optical band gap of the ZnO thin films was 3.26 eV. The optical constants (n,k)$(n,k)$ of the ZnO thin films in the wavelength range 300–1000 nm were obtained by infrared spectroscopic ellipsometry measurement. PL spectra of ZnO thin films showed strong UV near-band-edge emission peak at 376.5 nm and weak visible red emission at 643.49 nm using He–Cd laser as the light source, using a synchrotron radiation light source PL spectra showed three emission peak at 320 nm, 410 nm and 542 nm respectively.