Me-PTCDI thin film deposition on InSb(1 1 1)A

The evolution of N,N′-dimethylperylene-3,4,9,10-dicarboxyimide (Me-PTCDI) thin films formed by vapour deposition on InSb(1 1 1)A substrates has been studied by X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS) and low energy electron diffraction (LEED). XPS studies of the Me-PTCDI covered surface indicate that no significant interaction occurs at sub-monolayer coverage when compared to multilayer Me-PTCDI films. HREELS studies suggest only a weak interaction as evidenced by very small changes in the frequencies of several molecular vibrational modes. LEED patterns show the Me-PTCDI overlayer adopts a structure commensurate with the underlying InSb(1 1 1)A substrate surface and that can be rationalised by van der Waals intermolecular energy calculations for the Me-PTCDI unit cell. The results are consistent with a weak interaction at the Me-PTCDI/InSb interface, the formation of the commensurate structure being sufficient to overcome the small energetic penalty associated with deviation from the calculated intermolecular interaction energy minimum.     

拉曼光谱研究电化学沉积聚吡咯掺杂程度对膜厚度的依赖性

本文报道电化学沉积在光滑铂电极表面上聚吡咯 (PPy)膜的拉曼光谱。研究结果表明 :聚吡咯膜的掺杂程度在其生长过程中不断增加。因此 ,PPy膜的拉曼光谱特性对膜厚具有很强的依赖性。电化学分析结果也证明了这一发现。具有已知厚度的PPy膜的掺杂程度依赖于支持电解质的性质。     

Vibrational spectroscopy characterization of magnetron sputtered silicon oxide and silicon oxynitride films

Vibrational (infrared and Raman) spectroscopy has been used to characterize SiO_xN_y and SiO_x films prepared by magnetron sputtering on steel and silicon substrates. Interference bands in the infrared reflectivity measurements provided the film thickness and the dielectric function of the films. Vibrational modes bands were obtained both from infrared and Raman spectra providing useful information on the bonding structure and the microstructure (formation of nano-voids in some coatings) for these amorphous (or nanocrystalline) coatings. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis have also been carried out to determine the composition and texture of the films, and to correlate these data with the vibrational spectroscopy studies. The angular dependence of the reflectivity spectra provides the dispersion of vibrational and interference polaritons modes, what allows to separate these two types of bands especially in the frequency regions where overlaps/resonances occurred. Finally the attenuated total reflection Fourier transform infrared measurements have been also carried out demonstrating the feasibility and high sensitivity of the technique. Comparison of the spectra of the SiO_xN_y films prepared in various conditions demonstrates how films can be prepared from pure silicon oxide to silicon oxynitride with reduced oxygen content.     

Surface-enhanced Raman scattering study of silver deposition on thin Alq3 layers

Surface-enhanced Raman scattering (SERS) spectroscopy is applied to study in situ the interface formation of silver on thin Alq₃ films. The changes in the frequencies of Alq₃ vibrational modes are moderate and their line-shape is preserved upon Ag deposition. Moreover, a good correspondence appears between the SERS and powder spectra and frequencies predicted by density functional calculations for the meridianal isomer. The behaviour of Raman spectra indicates that no chemical interaction occurs between the Ag atoms and Alq₃ molecules.     

富硅氮化硅薄膜的制备及其光学带隙研究

采用双极脉冲磁控反应溅射法在不同参数条件下制备了一系列氮化硅薄膜。利用数字式显微镜和紫外-可见光光谱仪研究了沉积薄膜的表面形貌及其光学带隙,利用共焦显微拉曼光谱仪比较了硅衬底、氮化硅薄膜退火前后的拉曼光谱。结果表明,氮气流量对薄膜的光学带隙影响较大,制备的薄膜主要为富硅氮化硅薄膜。原沉积薄膜的拉曼光谱存在明显的非晶硅和单晶硅峰,退火处理后非晶硅峰减弱或消失,表明薄膜出现明显的结晶化;单晶硅峰出现频移现象,表明薄膜中出现硅纳米颗粒,平均尺寸约为6.6 nm。     

Raman光谱研究厚度对La0.9Sr0.1MnO3/Si薄膜结构的影响

通过溶胶-凝胶旋涂方法结合后退火工艺在Si（100）上制备了不同厚度的La_0.9Sr_0.1MnO₃（LSMO）薄膜,利用X射线衍射（XRD）和共焦显微拉曼散射（Raman）研究了LSMO/Si（100）薄膜的微结构．研究结果表明90 nm厚的LSMO薄膜具有正交相结构,当厚度大于150 nm时,薄膜具有菱方相结构. 150 nm厚的薄膜的Raman图谱中,490 cm^-1和602 cm^-1正交结构 关键词： 薄膜 1-xSr_xMnO₃')" href="#">La_1-xSr_xMnO₃ 共焦显微拉曼 微结构     

Effect of substrate temperature on the morphological,structural,and optical properties of RF sputtered Ge_(1-x)Sn_x films on Si substrate

In this study, Ge_(1-x)Sn_x alloy films are co-sputtered on Si(100) substrates using RF magnetron sputtering at different substrate temperatures. Scanning electron micrographs, atomic force microscopy(AFM), Raman spectroscopy, and x-ray photoemission spectroscopy(XPS) are conducted to investigate the effect of substrate temperature on the structural and optical properties of grown Ge Sn alloy films. AFM results show that RMS surface roughness of the films increases from 1.02 to 2.30 nm when raising the substrate temperature. This increase could be due to Sn surface segregation that occurs when raising the substrate temperature. Raman spectra exhibits the lowest FWHM value and highest phonon intensity for a film sputtered at 140?C. The spectra show that decreasing the deposition temperature to 140?C improves the crystalline quality of the alloy films and increases nanocrystalline phase formation. The results of Raman spectra and XPS confirm Ge–Sn bond formation. The optoelectronic characteristics of fabricated metal-semiconductor-metal photodetectors on sputtered samples at room temperature(RT) and 140?C are studied in the dark and under illumination. The sample sputtered at 140?C performs better than the RT sputtered sample.     

Diamond surface modification following thermal etching of Si supported hydrogenated diamond films by DBr

In this work, we study the modification of hydrogenated diamond films deposited on silicon resulting from its exposure to DBr followed by an annealing above 600 K, using high resolution electron energy loss spectroscopy (HREELS). This procedure results in silicon carbide SiC formation within the diamond film, as evidenced by the observation of a loss peak at 117 meV and its first harmonic at 233 meV in HREEL spectra. This diamond surface modification is interpreted as resulting from the reaction of products of the silicon support thermally activated etching with hydrogenated diamond.     

等离子体增强化学气相沉积法制备含氢类金刚石膜的紫外Raman光谱和X射线光电子能谱研究

利用脉冲辉光放电的方法,在硅片上采用不同的沉积工艺制备了含氢类金刚石膜层,并采用Raman光谱和X射线光电子能谱(XPS)对膜层进行表征.用Raman光谱仪在波长为325 nm的紫外光源的激励下观察膜层的键结构.紫外Raman光谱对含氢类金刚石膜是非常有用的,它能有效避免可见光Raman光谱测量时的荧光干扰,清晰地得到膜层的D峰和G峰.同时利用XPS分析得到膜层的sp3键含量,并与Raman光谱所得数据进行比较.通过Raman光谱和XPS分析可以发现,在紫外光源的激励下,膜层的G峰峰位向高频移方向移动,G峰峰位、I(D)/I(G),G峰半高宽和sp3键含量之间存在一定的关系.     

微喇曼和红外光谱法研究化学气相沉积金刚石多晶膜结晶质量特性

研究了化学气相沉积多晶膜的宏观性能（颜色和透光性）与微观性能（结晶质量、相纯度和氢杂质含量）之间的关系,喇曼谱与金刚石膜中氢杂质含量（红外光谱测得）的关联性.给出了根据颜色和透明度来区分样本膜质量的实验依据,颜色较深的膜的结晶质量差、相纯度低、氢杂质含量高,1 332 cm－1金刚石特征喇曼峰强度低,半峰宽大.由于多晶膜生长不均匀性、多晶以及粗糙度的影响,生长面的微喇曼光谱随采样点变化会产生较大的偏差,而光滑生长界面的喇曼光谱随采样点的变化偏差较小,因此生长界面的喇曼光谱更能反映化学气相沉积法制备金刚石膜的整体质量.     

Raman spectroscopy of sol–gel derived titanium oxide thin films

Raman spectra of TiO₂ films prepared via the sol–gel process were studied by UV and visible Raman spectroscopy. The evolution of the phases of TiO₂ films during annealing was investigated, and the relative intensities of the Raman bands excited with 325 nm were found to be distinct from those of the bands excited with 514 nm. The transmittance and FTIR spectra of the films annealed at different temperatures were characterized. The crystallization process of the powders and thin films treated by different annealing methods were also studied with Raman spectroscopy. The results show that the change in the relative intensities is caused by the resonance Raman effect. The anatase to rutile transition of the powder occurs at 700 °C, while that of the thin film occurs at 800 °C. The analysis of Raman band shape (peak position and full width at half‐maximum) after conventional furnace annealing and rapid thermal annealing indicates the influence of the non‐stoichiometry and phonon confinement effect. Copyright © 2011 John Wiley & Sons, Ltd.     

铜薄膜等离子改性及表面增强拉曼光谱的研究

表面增强拉曼光谱(surface-enhanced Raman spectroscopy, SERS)技术是一种基于探测吸附于金属基底表面分子振动光谱的快速无损检测方法,目前广泛应用于表面吸附、电化学催化、传感器、生物医学检测和痕量的检测与分析等领域。本实验采用直流磁控溅射技术在BK7玻璃基底上沉积一层厚度为50 nm的金属铜薄膜,在Ar离子轰击作用下获得不同表面粗糙度的金属铜薄膜样品,从而制备具有不同表面增强拉曼光谱活性的金属基底。实验样品分别通过X射线衍射仪（XRD）、原子力显微镜（AFM）、分光光度计、拉曼光谱仪表征其结构、表面形貌及光学性质。测试结果表明铜膜在Ar离子束轰击前后,样品X射线衍射谱的峰值强度没有发生变化,说明其晶相结构未发生改变;随着离子束能量的增加,薄膜表面粗糙度改变,光学散射强度随着表面粗糙度的增加而增强;离子束薄膜表面改性后,以罗丹明B(Rh B)为探针分子,表征薄膜样品表面增强拉曼的活性,通过对比不同样品表面Rh B的拉曼光谱,发现其光谱强度随金属铜薄膜样品表面粗糙度的增加而增强。     

Stress, microstructure and mechanical properties of graded multilayer tetrahedral amorphous carbon films

Tetrahedral amorphous carbon (ta-C) films deposited using a filtered cathodic vacuum arc (FCVA) system, have high intrinsic stress which limits their application as protective coatings. To reduce the film stress and to improve the adhesion, a multilayer structure is deposited at a gradient substrate negative bias from 1500 V to 80 V. This paper investigates the stress, microstructure and nano-mechanical properties of graded multilayer ta-C film on Si substrates. Compared with that of single-layer films deposited at optimised bias, the graded multilayer film has low stress without a decline in hardness and Young’s modulus. Microstructural evaluation of the multilayer film using visible Raman spectra shows that the average content of the sp³ bonds of the multilayer film remain at a high level. Nanoscratch testing illustrates favorable scratch resistance and good adhesion of the multilayer film. Scanning electron microscope (SEM) observation confirms the collapse of the film surface along the scratching trace. Finally, deposition on single crystal germanium substrates of a durable coating ∼ 1100 nm thick, and composed of three graded multilayer films is demonstrated. PACS 81.05.Uw; 81.15.Jj; 68.65.Ac; 68.55.Nq; 68.60.Bs     

Vibration spectroscopic study of the interaction of tris-(8-hydroxyquinoline) aluminum (Alq3) with potassium

The interaction between Alq₃ and potassium was studied by using Raman and infrared spectroscopies. Infrared reflection absorption spectroscopy (IRRAS) spectra of Alq₃ films show significant changes after potassium deposition, such as the appearance of new bands and changes in relative intensity. Surface-enhanced Raman scattering (SERS) spectra obtained using the 413.1 nm line of a Kr⁺ laser reveal similar changes. Changes are even more obvious when the 530.9 nm line was used for excitation. Changes in the SERS for excitation with the 413.1 nm line are less obvious due to a strong photoluminescence. The vibrational pattern of potassium-doped Alq₃ cannot be explained by the formation of radical anion by simple charge transfer, indicating the excess electron is not delocalized over the molecule. The observed spectral change suggests that the potassium atom interacts with both nitrogen and oxygen atoms of Alq₃ molecule.     

Raman spectroscopy of seized drugs and density functional theory interpretation

Abstract

The demand for a hand-held Raman spectrometer in the fast and accurate detection and identification of seized drugs is much higher than before, especially when facing unknown suspicious drugs. However, Raman spectra for the different drugs are less reported due to the inaccessibility of them. Here, we reported the experimental Raman spectra in detail of four typical drugs (such as methamphetamine, ketamine, caffeine, and magu). The Raman vibrational frequencies were also calculated by the method of density functional theory (DFT) at Becke-3-Lee-Yang-Parr (B3LYP) level with the 6-31?G and 6-31G(d,p) basis set. The results show that the experimental Raman spectra of these typical drugs are consistent with the theoretical Raman spectra. Using the potential energy distribution (PED) calculation with the GAR2PED program, the assignments of the observed Raman bands to the vibrational modes were presented. Further, methamphetamine and its camouflage N-benzylisopropylamine were analyzed by Raman spectroscopy and DFT calculations, and the result showed that the obvious differences of the Raman characteristic bands for these two samples could be found so that Raman technique could be used to identify the authenticity of methamphetamine. All the above results confirm the potential of the approach involving Raman spectroscopy combined with DFT calculations in the characterization of drugs. Based on this, the experimental spectra of seized drugs measured directly through a plastic package were studied. Raman spectroscopy has the advantage of being performed through packaging without disturbing the samples. Polypropylene transparent packaging does not alter the spectra of the drugs but will mask the corresponding bands if the Raman spectrum has a strong autofluorescence interference.     

Polymerization of Langmuir–Blodgett films of diacetylenes

Monolayer and multilayer assemblies of Langmuir–Blodgett films of 10–12 pentacosadyinoic acid (12–8 diacetylene) were deposited on flat gold substrates. Micrometre-size features were patterned by polymerization of the films by using standard electron beam lithography. Polymerized areas on a monolayer and bilayer, as well as multilayer films, were examined by scanning electron microscopy, atomic force microscopy and resonant Raman spectroscopy. It was established that polymerized areas on a monolayer and bilayer LB film adhere onto the gold substrate after development. The exposure curve, sensitivity, contrast and resolution of the polymer have been determined by using atomic force microscopy and correlated with the deposition conditions and molecular parameters. Stresses induced in the organic film during polymerization lead to an in-plane buckling of the micrometre-size polymer structure. A simple self-consistent theory was developed to predict critical strain and critical length of buckling. The observed effect of buckling of polymers might open an avenue for a wide range of important practical applications in the area of nanomechanical engineering.     

Research on Raman-scattering and Fabrication of Multilayer Thin Film with Different Structures and Components Based on Pt/Ti/Si3N4/SiO2/Si Substrate

选用三水醋酸铅、乙酰基丙酮酸锆、四异丙氧基钛、乙酰丙酮作初始材料,用同样的方法分别制备了锆钛酸铅(PZT)和钛酸铅(PT)两种固体前驱物. 采用改良型的溶胶-凝胶工艺技术,分别在不同的Pt-Ti-Si₃N₄-SiO₂-Si基底上,按照不同的组合方式,制备了三种多层薄膜：PZT、PT/PZT-PZT/PT、PT/PZT/-/PZT/PT. 较详细地讨论了薄膜制备的工艺技术,发现当凝胶通过烧结和干燥后变成固态物质时,薄膜内部存在着较大的残余应力,当薄膜在600 ºC下退火时其内部残余应力可以被减小. 通过拉曼     

Mechanical properties and platelet adhesion behavior of diamond-like carbon films synthesized by pulsed vacuum arc plasma deposition

Diamond-like carbon (DLC) is an attractive biomedical material due to its high inertness and excellent mechanical properties. In this study, DLC films were fabricated on Ti6Al4V and Si(1 0 0) substrates at room temperature by pulsed vacuum arc plasma deposition. By changing the argon flow from 0 to 13 sccm during deposition, the effects of argon flow on the characteristics of the DLC films were systematically examined to correlate to the blood compatibility. The microstructure and mechanical properties of the films were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) surface analysis, a nano-indenter and pin-on-disk tribometer. The blood compatibility of the films was evaluated using in vitro platelet adhesion investigation, and the quantity and morphology of the adherent platelets was investigated employing optical microscopy and scanning electron microscopy.The Raman spectroscopy results showed a decreasing sp³ fraction (an increasing trend in I_D/I_G ratio) with increasing argon flow from 0 to 13 sccm. The sp³:sp² ratio of the films was evaluated from the deconvoluted XPS spectra. We found that the sp³ fraction decreased as the argon flow was increased from 0 to 13 sccm, which is consistent with the results of the Raman spectra. The mechanical properties results confirmed the decreasing sp³ content with increasing argon flow. The Raman D-band to G-band intensity ratio increased and the platelet adhesion behavior became better with higher flow. This implies that the blood compatibility of the DLC films is influenced by the sp³:sp² ratio. DLC films deposited on titanium alloys have high wear resistance, low friction and good adhesion.     

Adsorption and electron properties of thin nickel films on W(110) surface

The evolution of the properties of ordered nickel films with thicknesses increasing from one to three atomic monolayers (ML) adsorbed on the W(110) single crystal surface is studied under ultrahigh vacuum conditions by the methods of reflection-absorption infrared spectroscopy (RAIRS) and ultraviolet photoelectron spectroscopy (UPS). The film structure corresponds to that of the Ni(111) single crystal face. The RAIRS technique is used to study the vibrational properties of the probing NO molecules adsorbed on the nickel films studied. In the course of the nickel film growth, whereby its thickness increases from 1 to 3 ML, both the vibrational and photoelectron spectra exhibit significant variation, which is indicative of a change in the adsorption and electron properties of the film. Stabilization of the IR and photoelectron spectra at a film thickness of 3 ML indicates that this thickness corresponds to the formation of the main adsorption and electron properties of the deposit. At the same time, the vibrational spectra of NO molecules adsorbed on a monoatomic nickel film exhibit features typical of adsorption on the W[110] surface of a massive tungsten crystal.     

Structure and orbital ordering of ultrathin LaVO3 probed by atomic resolution electron microscopy and Raman spectroscopy

Orbital ordering has been less investigated in epitaxial thin films, due to the difficulty to evidence directly the occurrence of this phenomenon in thin film samples. Atomic resolution electron microscopy enabled us to observe the structural details of the ultrathin LaVO₃ films. The transition to orbital ordering of epitaxial layers as thin as ≈4 nm was probed by temperature‐dependent Raman scattering spectroscopy of multilayer samples. From the occurrence and temperature dependence of the 700 cm^–1 Raman active mode it can be inferred that the structural phase transition associated with orbital ordering takes place in ultrathin LaVO₃ films at about 130 K.