Raman Spectra of AlP／GaP Short—period Superlattice

The samples of (AlP)n/(GaP)n short-period superlattics(period number n=4,6)grown by MOVPE and the sample of n-GaP(100)single crystal substrate are measured and analyzed by Raman spectrum.In the three kinds of samples,the double-phonon modes of first-order Raman scattering peaks are all existent.Moreover,the second-order Raman scattering peaks are observed to exist.     

Raman Scattering Spectrum Analysis of GaP and Its luminous Materials

Abstract: The Raman scattering spectra of n- type GaP(doped S) single crystal and red and green luminous materials grown on the n - type GaP (doped S) single crys-tal substrate by liquid - phase epitaxy are analyed. The results show that the spectra of GaP single crystal and its luminous materials include not only the first - order longitudi-nal optical photons and transverse optical phonons Raman scattering peaks, but also the peaks of the bound excitons, bound electrons and bound holes.     

掺杂超晶格的等离子激元与纵光学声子的耦合模

在T＝77K,测量出掺杂（Si)GaAs/AlGaAs超晶格的拉曼散射谱,观察到拉曼位移分别为223cm^-1和422cm^-1的两个光散射峰。理论分析认为,这两个散射峰是掺杂超晶格的等离子激元与纵光学声子耦合模引起的。这事模引起的光散射峰位置的理论计算值与拉曼测量结果相当一致。     

铌酸锂掺杂石英光纤拉曼增强特性研究

为了获得高拉曼增益特种石英光纤,提高拉曼光纤 放大器增益,本文研究了铌酸锂掺杂石英光纤的拉曼散射增强特性,采用改进化学气相沉积(MCVD)法制备出了铌酸锂掺杂石英光纤样品,其在1550nm 波长处的传输损耗为5dB/km。测得了铌酸锂掺杂石英光纤的拉曼光谱,并与相同长度的常 规单模光纤拉曼 光谱进行了对比,发现铌酸锂掺杂石英光纤具有更高的拉曼散射强度,在几个主要峰位处, 铌酸锂掺杂石 英光纤的拉曼散射强度为常规单模光纤的3.8～4.8倍。同时,搭建了 拉曼光纤放大器系统,分别测得铌酸 锂掺杂石英光纤和常规单模光纤的拉曼散射放大增益。实验结果表明,铌酸锂掺杂石英光纤 拉曼放大增益 约是常规单模光纤的2倍。因此,铌酸锂掺杂石英光纤作为拉曼光纤放大器的增益介质将可 取代常规单模 光纤,并能有效地提高拉曼光纤放大器的放大效果。     

InAlA5量子点材料的AFM和拉曼散射研究

对分子束外延（MBE）自组织生长的InAlAs量子点材料进行了拉曼散射实验。结合原子力显微镜（AnD对量子点形貌观察的结果,分析了InAlAs量子点生长过程中尺寸、密度和均匀性的改变,并研究了三维岛的结构对拉曼谱线的影响。对InAlAs淀积厚度不同样品的拉曼谱分析表明,岛状结构的尺寸横纵比与类GaAsLO模和类AlAs LO模的半高全宽有密切关系。不同偏振下的拉曼实验证实了该结构中的光学声子在Z（X,X）Z偏振条件下为非拉曼活性。     

Stimulated Raman Scattering in Nanorod Silicon Carbide Films

When the film is excited by a very low excitation energy, the spontaneous Raman scattering emerges. The intensity of Raman scattering is proportional to the excitation power below the threshold excitation. When the excited power reaches the excitation threshold, the intensity of Stokes light strongly increases. Meanwhile an anti Stokes light at 495 nm and multiple order but small Stokes peaks occur. The intensity of Stokes light is much larger than that of anti Stokes. The full width of half maximum (FWHM) of Stokes peak is reduced from 0.4 nm to less than 0.2 nm, the scattering angle between both Stokes and incident lights becomes less than 1°, and the angle between the Stokes and anti Stokes lights is about 3°. When the exciting power is in excess of the threshold, anti Stokes and multiple Raman scattering peaks reappear. These experiments can be unlimitedly repeated. From this experiment, we can exclude the possibility of spontaneous Raman scattering. It is suggested that the nanorods are a quantum line dimension having a large surface. There will be Raman differential scattering section so long as the nanorod films become very strong scattering media; the surface enhanced Raman scattering will be produced, the nanorod films of SiC will form a strong multiple scattering resonance cavities so as to form the stimulated Raman scattering oscillation.     

Forbidden Resonant Raman Scattering in GaAs/AlAs Superlattices: Experiment and Calculations

The Raman spectra of GaAs/AlAs(100) superlattices are calculated and studied experimentally for various wave-vector directions. The experiments are performed when applying a confocal optical microscope combined with a micro-Raman spectrometer for various scattering geometries both for phonons with a wave vector directed along the normal to a superlattice and in the in-plane geometry. The frequencies and eigenvectors of phonons are calculated in the extended Born model approximation taking into account Coulomb interaction in the rigid-ion approximation. The Raman spectra are calculated in the scope of the deformation- potential mechanism; herewith, it turns out that additional peaks, which are not described in the scope of this approach, appear in the experimental spectra. It seems likely that these peaks appear due to the manifestation of Raman scattering forbidden by selection rules under resonance conditions. An attempt is made to explain the appearance of these peaks in the experimental spectra within the scope of inelastic phonon scattering at bound charges (phonons with a large dipole moment).     

表面处理对CdTe Raman散射谱的影响

利用傅利叶变换喇曼散射技术研究了CdTe表面的Raman散射谱，观察到了CdTe表面光学声子（TO、LO）的一级、二级斯托克斯、反斯托克斯Raman散射峰。实验同时还研究了经过机械抛光、化学机械抛光、化学腐蚀等不同表面处理后的CdTeRaman散射谱。实验表明Raman散射方法除可以用来表征晶体表面的完整性外，还能有效地探测样品的表面沾污情况。总的来说Raman散射技术有希望成为器件工艺过程中的一种表面无损检测手段。     

Micro‐Raman Scattering Imaging of Langmuir–Blodgett Surface Relief Gratings

Surface relief gratings (SRGs) recorded on Langmuir–Blodgett (LB) films of an azobenzene homopolymer were visualized using micro‐Raman imaging. Raman scattering (RS) was achieved using the 780 nm laser line while pre‐resonance Raman scattering (pre‐RRS) and resonance Raman scattering were achieved using the 633 and 514.5 nm laser lines, respectively. Pre‐surface‐enhanced resonance Raman scattering (pre‐SERRS) and surface‐enhanced resonance Raman scattering (SERRS) were collected for the LB films covered with a 6 nm thick silver island film. The SRG could be chemically identified by the spatial variation in the Raman signal scattered by the film due to a concentration gradient. The pre‐SERRS provided signals of the same intensity along and across the grooves, indicating that the molecular architecture at the SRG surface is the same at the peaks as in the valleys.     

Phase transition of Cu2O to CuO nanocrystals by selective laser heating

In this paper, we reported the preparation of CuO nanocrystals by microwave irradiation method. With the aid of suitable surfactants, CuO nanoparticles of uniform size and shape were successfully prepared. The as-prepared nano-products were characterized by different techniques such as Xray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM), which all confirmed the good quality of the product. However, Raman spectra showed some peaks, which were attributed to impurity phases such as Cu₂O or Cu(OH)₂. Post annealing the samples by laser is a good method to convert these phases into pure CuO. Phase transition was observed in situ by Raman spectroscopy. After laser treatment process, Raman spectra of the samples showed that the nano-product is single phase and the crystal quality of CuO nanocrystal was improved clearly.     

GaNAs的声子拉曼散射研究

对分子束外延生长的GaNAs外延层进行了拉曼散射研究,观测到了由于导带中的E＋态所引起的共振散射和由此产生的布里渊区非Г点声子的拉曼峰,清晰地观测到了随氮含量增大,氮在GaAs中的局域模振动演变为GaNAs中的类GaN晶格声子带模。通过样品在850度快速热退火前后拉曼谱的对比,推测地指认了两个与氮的成对或成团效应有关的振动峰。     

液芯波导对溶液拉曼光谱探测灵敏度的放大

采用折射率比石英(1．46)低的Teflon-AF(n=1.29)液芯波导系统。研究了乙醇和四氯化碳溶液的拉曼光谱，通过利用液芯波导的内全反射特性。延长激发光对波导管内的溶液试样的总的有效激发光程。并有效增强对光谱信号的收集，成功地采集到四氯化碳和乙醇的拉曼光谱。并与采用常规90度几何散射结构获得的拉曼光谱进行了对比，表明液芯波导系统可以使拉曼光谱信号强度增强200倍以上，并大大提高探测灵敏度和信噪比。展示了液芯波导拉曼光谱应用于化合物溶液的微量分析、生物医药成分的定量检测、临床医学诊断中对病理样本的微量分析和定量检测等领域的可行性，为进一步采用液芯波导拉曼光谱进行定量标定的研究工作和实际应用提供了实验依据。这项技术也适合于对其它包含多种成分的复杂的生物体系和化学药品进行定量分析，具有巨大的应用前景和实际价值。     

激光偏振拉曼的CVD多晶石墨烯表征

石墨烯具有优异的物理化学性质,在MEMS器件、光电检测材料、柔性显示屏、新能源电池、复合材料等方面成为研究热点。目前大面积石墨烯制备主要依赖于化学气相沉积技术(chemical vapor deposition, CVD),但其生长的晶体质量直接影响到电化学特性和实际应用,因此需要一种快速而准确的表征方法。实验利用背向散射的偏振激光散射装置测量CVD生长的石墨烯拉曼光谱。通过分析实验获得的300 nm SiO2/Si基底上的单层、五层和十层左右的石墨烯角分辨偏振拉曼光谱,发现单层生长的石墨烯偏振特性与机械剥离单晶石墨烯一致;随着层数的增加,G峰偏振响应差异更加明显,表现出明显的椭圆特性;在不同石墨烯层数上的D峰也呈现出一定的偏振响应差异性。偏振拉曼测试结果表明目前CVD生长的缺陷和多晶特性与石墨烯层数呈现正相关特征。     

组分离子浓度对铁电铌酸钾锂晶体Raman光谱的影响

测量了一批不同组分的铌酸钾锂晶体Raman光谱,发现晶体中位于C格位的Li离子浓度对晶体Raman光谱产生了强烈的影响：低Li含量晶体中[NbO6]^7-八面体所对应的3个Raman特征光谱线没有发生峰分裂,在100～400cm^-1范围出现的小峰与C格位Li离子浓度相关;当晶体中Li离子浓度增加时,与v5所对应的Raman峰在散射几何为X（ZY）Z对应的光谱中加宽．v2振动模式在两种散射几何中均出现分裂峰,并在100～400cm^-1范围出现小峰数量增多;当Li离子浓度接近晶体化学组分时,微扰进一步加强,v5所对应峰分裂成3个峰,v1和v2振动模式发生部分分裂,在100～400cm^-1范围小峰更为突出．     

钨酸钡单晶的生长及其受激拉曼特性

采用提拉法生长出了BaWO4 晶体。采用波长532nm的皮秒激光激发,观察到室温下的受激拉曼光,对受激拉曼光斑进行了讨论。在散射光谱中观察到从484到755nm共8条谱线,测得第一级斯托克斯光和第二级斯托克斯光的阈值分别为3. 5mJ和6. 5mJ。晶体的抗强光损伤大于20GW / cm2。     

共溅射钨硅化合物真空快速热退火行为(英文)

The behavior of co-sputtering tungsten silicide after vacuum rapid annealing at 1000-1100℃ for 15s is investigated by Raman scattering, scanning electron microscope, X-ray diffraction, Auger electron spectrum and resistivity measurements. There are two Raman peaks at 331 and 450cm-1, and their intensities increase with the temperature rise of rapid thermal annealing. Scanning electron micrograph exhibits crystallization at 1000℃ and its enhancement with increase of annealing temperature. In addition to the (002), (101), (110), (103), (112) and (200) diffraction peaks of WSi2, there are some W5Si3 peaks in X-ray diffraction pattern. However, the composition of WSi2 is found in Auger electron spectrum at 1000℃, and the measurement results of sheet resistance also conclude WSi2 characteristics.     

人脑硫氧还蛋白还原酶的光谱学研究

在紫外光诱导硫氧还蛋白还原酶(TrxR)产生荧光光谱的实验基础上，对TrxR溶液的谱线特性及其产生机理进行了研究。实验结果表明，在波长为253．7nm的紫外光激励下，TrxR溶液能够产生较强的荧光，其光谱覆盖了280～720nm的范围，谱峰形状主要由两个宽阔的峰及分布在宽峰上的诸多细锐的次峰组成；随着TrxR溶液浓度的改变，宽峰和锐峰分别表现出不同的变化趋势。根据分子内部能量转换理论以及共振拉曼散射理论，对TrxR产生的荧光光谱的机理进行了理论分析。理论和实验研究结果均表明中心波长位于336nm的宽峰是来自于TrxR分子中的色氨酸的荧光峰，而诸多锐峰则是TrxR分子的共振拉曼散射。对波长为253．7nm的紫外光激励的TrxR溶液荧光光谱的研究有助于研究溶液状态下TrxR分子的构像、结构以及分子的电子振动态等。     

Correlation between intersubband Raman scattering and electric-field domains in quantum-well structures

We report on Raman scattering by intersubband excitations in GaAs---AlAs superlattices which exhibit electric-field domains resulting from sequential resonant tunneling. At a given bias, the Raman spectra reveal two peaks in voltage ranges where two domains coexist. An unexpected result of our studies is the observation of significant differences in the dependence of charge- and spin-density scattering on the electric field.     

GaN和p型GaN薄膜中声子模和缺陷模的变温喇曼散射

研究了MOCVD生长的GaN及掺Mg GaN薄膜从78到578K下的喇曼散射谱.在GaN和掺Mg GaN的谱中都观察到一个位于247cm-1的峰,此峰被认为是缺陷诱导的散射峰,而非电子散射和Mg的局域模.同时讨论了两个谱中E2和A1(LO)声子峰的频率和线形.在掺Mg GaN样品中观察到应力松弛现象.     

Free carrier absorption and lattice vibrational modes in bulk ZnO

The electronic properties of semiconductors are highly dependent on carrier scattering mechanisms determined by crystalline structure, band structure, and defects in the material. Experimental characteristics of lattice vibrational modes and free carrier absorption in single-crystal ZnO samples obtained from different sources are presented in this work to provide a further understanding of carrier scattering processes pertaining to electronic properties. Infrared absorption measurements indicate strong absorption peaks due to a combination of optical and nonpolar phonon modes in the 9–13 μm spectral region. The Raman spectra obtained for these samples similarly reveal the presence of these phonon modes. Infrared absorption measurements also demonstrate free carrier absorption in the 3–9 μm spectral region for higher conductivity samples, where a λ^m dependence is observed with m=2.7–3, indicating both longitudinal optical phonon scattering and ionized impurity scattering. From these results, we show that infrared absorption can be used as a routine nondestructive technique to determine the material characteristics and quality of bulk ZnO.