聚四氟乙烯F-C-F伸缩振动二维红外光谱研究

在303~393K的温度范围内,测定聚四氟乙烯F-C-F伸缩振动模式(νCF2)的一维红外光谱。研究发现:1220cm-1的红外吸收峰归属于聚四氟乙烯F-C-F不对称伸缩振动模式(νasCF2),而1150cm-1的红外吸收峰则归属于聚四氟乙烯F-C-F对称伸缩振动模式(νsCF2)。进一步研究了聚四氟乙烯νCF2的二阶导数红外光谱、四阶导数红外光谱,发现聚四氟乙烯νasCF2在1210cm-1和1260cm-1处裂分为双峰;而聚四氟乙烯νsCF2则在1145cm-1、1155cm-1和1175cm-1裂分为3个吸收峰。最后研究了聚四氟乙烯二维红外光谱,考察了温度对于聚四氟乙烯νCF2吸收强度变化的影响。研究发现:随着测定温度的升高,聚四氟乙烯νCF2红外吸收强度变化快慢的顺序为:1145cm-1>1210cm-1>1155cm-1>1175cm-1>1260cm-1。本项研究拓展了二维红外光谱在聚四氟乙烯热变性方面的研究范围。     

Dual detection biosensor based on porous silicon substrate

Due to the high surface-to-volume ratio (hundreds of m²/cm³) porous silicon became during the last years a good candidate material as substrate for biosensor application. Moreover, the versatility of surface chemistry allows different functionalization approaches and large number of molecules to be captured on well-defined areas. This paper reports a dual detection method for protein recognition processes developed on different nanostructured porous silicon (PS) substrates, based on using two complementary spectroscopic techniques: fluorescence and electrochemical impedance. The structures were tested for biomolecular recognition – biotin–strepavidin couples – in order to achieve an optimum surface for protein's immobilizations. Comparative analyses of the attachment degree and preservation of the biomolecules activity on the porous silicon surfaces and silicon slides are also described.     

二甲基硅油 C-Si 伸缩振动模式红外光谱研究

在303~393 K温度范围内,采用变温傅里叶变换衰减全反射红外光谱技术(ATR-FTIR)研究了二甲基硅油的一维红外光谱、二阶导数红外光谱、四阶导数红外光谱和去卷积红外光谱。实验发现,在1800~600 cm~(-1)范围内,二甲基硅油主要存在CH_3伸缩振动模式(νCH_3)、CH_3变形振动模式(δCH_3)、CH_3摇摆振动模式(ρCH_3)、Si-O伸缩振动模式(νSi-O)和Si-C伸缩振动式(νSi-C)等5种红外吸收模式,其中782 cm~(-1)和789 cm~(-1)处的红外吸收峰归属于二甲基硅油νSi-C。以二甲基硅油νSi-C为研究对象,进一步开展相关二维红外光谱的研究。结果发现,随着测定温度的升高,二甲基硅油νSi-C红外吸收强度的变化快慢顺序为:789 cm~(-1)782 cm~(-1)。本项研究拓展了ATR-FTIR技术在二甲基硅油热变性方面的研究范围。     

硅氧树脂 Si-O 键伸缩振动模式ATR红外光谱研究

在303~393 K 温度范围内,采用变温傅里叶变换衰减全反射红外光谱(ATR-FTIR)技术分别测定硅氧树脂的一维红外光谱、二阶导数红外光谱和四阶导数红外光谱。研究发现,在1800~600 cm-1范围内,聚硅氧树脂主要存在着 CH 3伸缩振动模式(νCH3)、CH 3变形振动模式(δCH3)、CH 3摇摆振动模式(ρCH3)、Si-O 伸缩振动模式(νSi-O )和 Si-C 伸缩振动模式(νSi-C )。在1100~1000 cm-1范围内,以νSi-O 为研究对象,研究了温度对硅氧树脂分子结构的影响。实验发现,随着测定温度的升高,硅氧树脂νSi-O 的主要红外吸收频率出现了明显的红移现象。进一步研究了硅氧树脂νSi-O 的二维红外光谱,考查温度对于νSi-O 红外吸收强度的影响。研究发现,随着测定温度的升高,硅氧树脂νSi-O 红外吸收强度的变化快慢顺序为：1024 cm-1>1096 cm-1>1010 cm-1>1076 cm-1>1083 cm-1>1064 cm-1。本研究拓展了 ATR-FTIR 技术在硅氧树脂材料热变性方面的研究范围。     

Influence of Ga content on defects in CuInxGa1 − xSe2 based solar cell absorbers investigated by sub gap modulated photocurrent and admittance spectroscopy

In this work, we investigate the influence of gallium content on the defects properties of co-evaporated CuIn_xGa_1 − xSe₂ by sub gap modulated photocurrent spectroscopy and admittance spectroscopy techniques. A series of CuIn_xGa_1 − xSe₂ based solar cells with different gallium content in the range from 0% to 33%, and with the same CdS buffer layer have been investigated. On one hand, photocurrent spectroscopy results show 2 types of defects named D1 and D2, and on the other hand, admittance spectroscopy results exhibit only one type of defect. I-V curves show that one of the two defects probed by photocurrent is responsible of the dominant recombination mechanisms next to the heterointerface, between the absorber and the buffer layers. Moreover, I-V curves under AM 1.5 conditions show that the cell with no probed D2 defect presents the best photovoltaic performances.     

The use of near-infrared spectroscopy for the quantitation of a drug in hot-melt extruded films

The objective of the study was to demonstrate the utility of near-infrared spectroscopy (NIRS) for quantitative analysis of a model drug in hot-melt extruded film formulations. Polyethylene oxide (PEO) films with clotrimazole (CT) as a model drug were prepared by hot-melt extrusion (HME) incorporating drug concentrations ranging from 0-20% and analyzed using a Fourier transform near-infrared (FT-NIR) spectrophotometer in the reflectance mode. High performance liquid chromatography (HPLC) was the reference method used for this study. The NIR calibration model derived for CT was composed of 21 frequency ranges that were correlated to the values quantified using the HPLC reference method. The NIR method developed resulted in an assayed CT amount in the film matrix to be within 3.5% of the quantity determined by the reference method. These studies clearly demonstrate that NIRS is a powerful method for the quantitation of active drug substances contained in films produced by HME and warrants further investigation.     

Synthesis and characterization of Ag-Ni bimetallic nanoparticles by laser-induced plasma

We present an approach in which laser ablation deposition is used to synthesize silver-nickel bimetallic nanoparticles. A variety of techniques, including scanning electron microscopy, energy disperse spectroscopy and X-ray photoelectron spectroscopy have been used to characterize the morphology, composition and construction of synthesized bimetallic nanoparticles, respectively. The formation mechanism of bimetallic nanoparticles has been discussed. The Raman spectra of silver-nickel bimetallic nanoparticles have been analyzed. Time-of-flight mass spectrometry has been applied to directly measure intermediate species. The results indicate that diatomic AgNi is the most abundant species and suggest that the AgNi is the most stable intermediate which may play an important role in the synthesis process. Emission spectra demonstrate that the electron temperature is in the range of 6000-10000 K during the ablation process and increases with the laser power density.     

Luminescent graphene quantum dots from oxidized multi-walled carbon nanotubes

Fluorescent nano-graphene quantum dots (GQD) were isolated from oxidized carbon nanotube suspension with the aid of cysteamine. The oxidized GQD were thiol functionalized with cysteamine in presence of dicyclohexylcarbodiimide as coupling agent. The GQD chemistry and morphology were characterized by means of X-ray photoelectron spectroscopy and atomic force microscopy. The thiolated graphene quantum dots exhibit an intense luminescence (quantum yield around 10%) in the visible range with an excitation wavelength-dependent fluorescence.     

BTF炸药分子的结构分析

苯并三呋喃氮氧化合物(BTF)是一种新型高性能炸药,其分子结构中不含有氢,分子结构具有一定的特殊性。本文利用傅里叶红外光谱(FTIRSpectroseopy),拉曼光谱(RAMAN Spectroscopy)以及有机质谱(MS)详细分析了BTF的分子结构,阐明BTF分子中的六元环介于苯环和饱和六元环之间,分子中含有“准硝基”结构,分子呈现共平面性以及强的共轭效应。     

Absorption and emission spectra of the YBCO laser plume

The plasma produced during laser ablation deposition of thin film YBCO has been studied by optical emission spectroscopy. There is evidence of increased YO band emission in the range 590–625 nm as the ambient oxygen gas pressure confining the plume is increased in the range 30–200 m Torr. Temporal profiles show that close to the target the plume is insensitive to ambient oxygen pressure. It is deduced that the optical emission here is excited by electron impact excitation. Further away from the target there is evidence that two distinct processes are at work. One is again electron excitation; the emission from this process decreases with distance because the expanding plume cools and collisions become less frequent in the expanding gas. The second is driven by oxidation of atomic species expelled at high speeds from the target. The main region of this activity is in the plume sheath where a shock front ensures heating of ambient O₂ and reaction of monatomic plasma species to form oxide in an exothermic reaction. Spatial mapping of the emission demonstrates clearly how increasing oxygen gas pressure confines the plasma and enhances the emission intensity from the molecular YO species ejected from the target in a smaller region close to the target. Ba⁺ is observed as a dominant species only very close to (within 1 mm of) the target. Absorption spectra have been taken in an attempt to examine ground state and cool species in the plume. They reveal the quite surprising result that YO persists in the chamber for periods up to 1 msec. This suggests an explanation for the recent report of off-axis laser deposition in terms of simple condensation. Previously, quasi-ballistic transfer of material from target to substrate has been considered the only significant process.     

Enhancement of photoluminescence in Er-doped Ag-SiO2 nanocomposite thin films: A post annealing study

Silver-silica (with Ag 2.8 at.% and 8.7 at.%) nanocomposite (NC) thin films doped with Er⁺³ (0.1-0.9 at.%) were synthesized by atom beam co-sputtering using 1.5 keV Ar atoms. Optical absorption and photoluminescence (PL) studies of pristine and annealed films were performed, together with Rutherford backscattering and secondary ion mass spectroscopy studies for elemental characterization of the NC films. Optical absorption results of pristine and annealed NC film (with Ag ∼8.7 at.%) confirmed the formation of Ag nanoparticles evidenced by the appearance of characteristic surface plasmon resonance absorption features. Photoluminescence (PL) studies, carried out using Ar Laser pumping at 0.488 μm, the wavelength that the Er ions can absorb resonantly, indicated the presence of PL emission around 1.54 μm in the case of all the as-synthesized samples. The observed PL peak corresponds to the atomic transitions of Er as reported in literature. A relative enhancement in the intensity of PL peak has been observed after annealing the NC films. In the case of NC film with 0.9 at.% Er and 8.7 at.% Ag, the enhancement in PL intensity is almost twice, with respect to the as-deposited sample, for a heat treatment of about 1 h at 600 °C in a nitrogen atmosphere. However for a NC film with Er 0.1 at.% + Ag 2.8 at.%, the PL intensity is enhanced by approximately 3.7 times after annealing at 400 °C for 1 h in nitrogen atmosphere. Since the samples with surface plasmon resonance (SPR) did not show the PL enhancement, the role of SPR in the enhancement of the PL is ruled out. The enhanced PL emission from Er and Ag codoped silica indicates that the Er photo-stimulation is mediated by the energy transfer from Ag nanostructures or ions to Er. Lifetimes of PL peaks for the pristine and annealed samples were also studied. The observed lifetime ∼10 ms is a good indication of excellent PL efficiency.     

Comment on “Argon I Lines Produced in a Hollow Cathode Source, 332 nm to 5865 nm”

Recent observations at the National Institute of Standards and Technology indicate that the Ar I wavenumbers reported by Whaling et al. [J. Res. Natl. Inst. Stand. Technol. 107, 149 (2002)] are systematically too large. To investigate the source of this problem, selected lines of Ar I and Ar II were remeasured in the same spectra used by Whaling et al. The measurements show that the Ar I wavenumbers of Whaling et al. are systematically shifted with respect to the Ar II wavenumbers previously reported by Whaling et al. [J. Quant. Spectrosc. Radiat. Transfer 53, 1 (1995)] based on the same spectra. The Ar I wavenumbers can be corrected by a constant multiplicative correction of 0.999 999 933.     

An organic antitarnish coating on tinplate

For protecting tin from tarnishing, laurylamine has been found to be more effective than other antitarnish agents. A 10 min treatment in 2.5 g dm⁻³ of laurylamine solution at pH 8 and 70 °C forms a coating on tinplate with better protective ability and good solderability. The results of X-ray photoelectron spectroscopy and Auger electron spectroscopy analyses show that the coating formed has the average composition of 39.0% O, 48.7% Sn, 7.9% N and 4.4% C. From differences in the binding energies of Sn and N before and after film formation, it is deduced that N in laurylamine is coordinated with Sn in the film.     

Structural rearrangement at the yttrium-depleted surface of HCl-processed yttrium aluminosilicate glass for Y-microsphere brachytherapy

The design of a process to create yttrium aluminosilicate microspheres with a core–shell structure is of interest in the field of cancer brachytherapy. Glass microspheres with yttrium-depleted shell may indeed reduce the risk of ⁹⁰Y release into the organism. Here we show – by means of confocal micro-Raman scattering, microfluorescence, X-ray-fluorescence analysis, and IR spectroscopy – that yttrium depletion may be achieved by etching in HCl solution (pH 2) at a rate of 1 μm day⁻¹ in bulk glass and 3 μm day⁻¹ in glass microsphere (35 μm of diameter). Importantly, the spectroscopic results – collected in confocal configuration along the processed layer – indicate a high degree of structural reconstruction of the glass network, with the formation of an interconnected silicate-rich glass that surrounds a core of unmodified yttrium aluminosilicate. We also demonstrate that the process is driven by non-bridging oxygen sites, which regulate the hydroxylation and structural reconstruction of the glass within the Y-depleted layer. The analysis gives also some insight into open fundamental questions about the short-range structure and the chemical stability of this kind of glass, which is also important in photonics and nuclear waste disposal.     

Diffusion during annealing of Al/Cu/Fe thin films

The Al-Cu-Fe system is interesting due to the existence of the quasicrystalline phase Al_62.5Cu₂₅Fe_12.5 as well as its approximant phases. A two-step procedure of thin film preparation is considered: deposition of a multilayer structure of individual elements and consequential annealing. To analyze the diffusion processes trilayers of individual elements were deposited by sputtering with a total thickness of about 400 nm. Afterwards, the samples were annealed in tube furnace in inert atmosphere. Rutherford backscattering spectrometry, Auger electron spectrometry and X-ray diffraction were used to quantify the depth profiles. The results point out to a three-stage process as a function of rising temperature: first Al and Cu form the γ-Al₄Cu₉ compound layer; second the aluminium spreads throughout the film with copper and iron mainly divided. The β-Al(Cu,Fe) phase is observed. Complete homogenization is followed afterwards.     

Synthesis of BaMoO4:Er/Yb particles by an MAM method and their upconversion photoluminescence properties

Er³⁺-doped BaMoO₄ (BaMoO₄:Er³⁺) and Er³⁺/Yb³⁺ co-doped BaMoO₄ (BaMoO₄:Er³⁺/Yb³⁺) particles were successfully synthesized by a cyclic microwave-assisted metathetic (MAM) method, and show fine and homogeneous morphology with particle sizes of 0.5–1 μm. At 980-nm excitation, BaMoO₄:Er³⁺ and BaMoO₄:Er³⁺/Yb³⁺ particles exhibited a strong 525-nm emission band and a weak 550-nm emission band in the green region. The Raman spectrum of BaMoO₄:Er³⁺/Yb³⁺ particles indicated the appearance of additional peaks at higher frequencies (390 and 505 cm⁻¹) and at lower frequencies (218 and 255 cm⁻¹).     

N2-COIL的氧发生器水汽诊断

在氧碘化学激光（COIL）系统中，水汽是影响激光器输出功率的最重要原因之一，因此测控氧发生器（SOG）出口气流中的水汽含量非常重要．文中利用吸收和发射光谱法对方管式射流氮气氧碘化学激光器（N2-COIL）的氧发生器分别进行了水汽含量测量．测量结果显示，在保持氯气流量一定的前提下，该发生器正常工作状态下水汽百分含量小于9％，且随氧发生器的总压的增加而减小，随氮气流量的增大而增加．该结果表明，气体流速是引起水含量变化的主要原因．     

Evolution of Si (and SiC) nanocrystal precipitation in SiC matrix

Si_1−xC_x films with varying ratio of carbon to silicon (C/Si) were fabricated by magnetron co-sputtering from a combined C and Si target. The composition in films was changed by adjusting the ratio of sputtered target's area between C and Si. Analysis of X-ray photoelectron spectroscopy for as-deposited films shows that C/Si atomic ratios of our films have ranges of 0.33-1.02. Thermal annealing of as-deposited films was carried out at various temperatures from 800 to 1100 °C in a conventional furnace. Fourier transform infrared spectra show a shift of Si-C stretching peak towards higher wavenumbers from ∼ 737 cm^− 1 to ∼ 800 cm^− 1 with increasing annealing temperature. From the results of Raman spectroscopy, X-ray diffraction and transmission electron microscopy, it was found that the dominant type of nanocrystals changes from Si to SiC in the films annealed at 1100 °C when the C/Si atomic ratio increases from 0.33 to 1.02.     

高速微晶硅材料的制备及其特性分析

本文采用甚高频等离子体增强化学气相沉积技术制备出了系列不同功率的微晶硅薄膜.对薄膜的电学特性和结构特性进行了测试分析,结果表明:制备出了光敏性在500～700、激活能在0.5 eV左右、沉积速率大于0.8 nm/s和晶化率在60%左右的微晶硅材料.同时也对材料的稳定性进行了相关的研究.     

Modification of polycarbonate surface by Ar ion implantation for various opto-electronic applications

The samples of polycarbonate were implanted to 100 keV Ar⁺ ions at fluences ranging from 1 × 10¹⁵ to 2 × 10¹⁶ ions/cm². The effect of ion implantation on DC conductivity and optical behaviour of this polymer has been investigated. The observed changes have been correlated with the induced structural changes in the implanted layer using Raman spectroscopy. The increase in electrical conductivity, decrease in UV-visible transmission and red shifting of the optical absorption edge may be due to the formation of a three dimensional carbonaceous structure having conjugated double bonds in the near surface layer of polycarbonate as a result of ion implantation. The shift in the conduction mechanism in the implanted layer from ohmic towards SCLC has been observed as a function of implantation dose. The novelty of the present study is to investigate the implantation induced electrical conduction mechanism in the implanted polycarbonate and to comprehend it with induced optical behaviour for its utilization as optically active material with conductive surface in various opto-electronic devices.