新型多氮杂环金属配合物的合成及其光谱研究

采用溶液析出法,合成了以2-（2′-羟基-5′-甲基苯基）苯并三唑（HMPB）为配体的多氮杂环金属配合物M（HMPB）2（M=Co,Ni）,利用元素分析、激光解析飞行时间质谱等进行了表征,并研究了新配合物的红外特征光谱和紫外-可见电子吸收光谱。结果表明：HMPB配体通过N和O原子与中心金属以二齿形式配位,中心金属的配位数为4;配合物红外特征吸收谱带位于400～2 500 cm^-1,形成金属配合物后,2-（2′-羟基-5′-甲基苯基）苯并三唑的羟基的伸缩振动吸收、CN振动峰和C─O特征吸收有明显改变,同时确定了配位键M─N和M─O的特征峰位置;配合物在紫外区有强吸收,其最大吸收峰位于335～345 nm。

Optical and surface properties of hybrid TiO2/ormosil planar waveguide prepared by the sol-gel process

Two kinds of silanes, 3-glycidoxypropyltrimethoxysilane (GLYMO) and 3-trimethoxysililpropylmethacrylate (TMSPM), were used to prepare ormosil waveguide films by the sol-gel method. Thirty percent Ti(OBu)(4) and 70% silane were contained in the precursor sets. The properties of films were measured by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV/VIS/NIR spectrophotometer (UV-vis), atomic force microscopy (AFM), m-line and scattering-detection method. The films from GLYMO and TMSPM precursors exhibit similar thickness (2.58 mu m for GLYMO, 2.51 mu m for TMSPM) and refractive index (1.5438 for GLYMO, 1.5392 for TMSPM, lambda=632.8 nm), but the film from TMSPM precursor has higher propagation loss (1.024 dB/cm, lambda=632.8 nm) than the film prepared from GLYMO (0.569 dB/cm, lambda=632.8 nm). Furthermore, the film prepared from TMSPM is easy to be opaque and cracks during coating whereas the same phenomenon was not found for the film prepared with GLYMO. It is confirmed that GLYMO is a better precursor than TMSPM for waveguide film preparation. (C) 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

不同贮藏条件下果实角质层成分及其与耐贮性关系研究

角质层是果实抵御外界环境胁迫的一个屏障，既能调节果实自身的生理活动，也能增加对病原菌入侵的抵抗力，在果实贮藏保鲜中具有重要的作用。本文利用傅里叶变换红外光谱检测（Fourier-transform-infrared-spectroscopy）法，重点研究了不同贮藏条件下果实角质层和果肉细胞壁成分变化，及对果实品质和贮藏性的影响，为进一步阐明角质层在果实贮藏保鲜中的作用提供依据。研究内容包括：（1）壶瓶枣果实在冷藏和气调下软化率、品质、角质层和果肉细胞壁成分变化；（2）即时冷藏和延迟冷藏下，桃果实好果率、品质、角质层和果肉细胞壁成分变化；（3）采前喷施氯化钙或油菜素内酯对甜樱桃单果重、品质、果肉细胞壁结构以及耐贮性的影响。 试验结果表明：（1）与冷藏（-1±1 ºC）相比，气调贮藏（10% O2 + 0% CO2， -1±1 ºC）能够显著降低壶瓶枣软化率，更好地保持果实的硬度、可溶性固形物（SSC）和可滴定酸（TA）含量以及较高含量的果肉细胞壁物质和较低含量的角质层物质。（2）与延迟冷藏（25 ºC，48 h后转入0 ºC）相比，即时冷藏使“八月脆”桃果实能保持较高的果实硬度和好果率，显著减慢TA含量下降，能保持较高含量的果肉细胞壁物质和角质层物质，但对SSC和Vc含量没有显著的影响。（3）与对照相比，采前喷施CaCl2（1%，m/v）能够增加“红灯”（6.94%）的单果重，对甜樱桃果实的品质指标（硬度、SSC、TA）和细胞壁结构没有明显的影响。（4）与对照相比，采前喷施0.15 mg•L-1油菜素内酯能增加“红灯”（3.68%）和“大紫”（8.61%）的单果重，降低“红灯”果实的自然腐烂率，并不影响果实的品质指标（硬度、SSC、TA）。 这些研究结果说明：（1）与冷藏（-1±1 ºC）相比，气调贮藏（10% O2 + 0% CO2， -1±1 ºC）更利于壶瓶枣果实贮藏保鲜；（2）与延迟冷藏（25 ºC，48 h后转入0 ºC）相比，即时冷藏（0 ºC）更利于“八月脆”桃果实贮藏保鲜；（3）气调贮藏和即时冷藏通过调节果实角质层和细胞壁代谢等途径发挥作用。气调贮藏会降低壶瓶枣果实角质层物质含量，增强其透气性，减少壶瓶枣酒软发生；但即时冷藏会延缓“八月脆”桃果实角质层降解，维持角质层物质较高的含量以及结构完整性，以充分发挥角质层的保护作用，减缓果实的软化进程，维持果实硬度和品质；（4）采前适当浓度的钙或油菜素内酯处理对增加甜樱桃单果重，降低自然腐烂率有一定的作用，但在不同品种中的作用效果有差异。

土地利用变化对西双版纳地区土壤及植被碳含量的影响

土地利用变化，尤其是热带地区森林生态系统土地利用方式的变化极大地改变了全球碳循环，对大气CO2浓度的升高，气候变暖等全球性环境问题起着不可忽视的作用。同时，森林的大面积破坏，引起土壤流失，营养元素含量降低，土壤健康状况恶化，最终大幅度降低生态系统的生产力。本文主要结合野外实地调查和室内分析的方法，研究森林砍伐后转变为农田和橡胶园对西双版纳热带地区土壤碳、氮、磷含量以及有机质化学结构的影响，天然次生林恢复、橡胶园建设对大气CO2的蓄积作用。 森林砍伐后转变为农田和橡胶园，显著地改变了土壤的理化特性。研究结果表明，与次生林相比，农田和橡胶园表层土壤容重、pH值升高，含水量降低，有机质、全氮、全磷、速效氮、有效磷含量显著降低。土地利用变化对土壤特性的影响主要发生在0-40 cm 表层土壤，而对40 cm以下土层影响较小。 土地利用变化改变土壤碳含量，同时影响土壤有机质的化学结构。胡敏酸紫外-可见光谱(UV-VIS)、傅利叶变换红外光谱 (FT-IR) 分析发现，不同生态系统表层土壤 (0-20 cm) 胡敏酸光谱学特性存在明显差异。次生林E4/E6值高于农田和橡胶园。与次生林相比，农田和橡胶园表层土壤有机质中酚基相对含量显著降低，脂肪族、芳香族、羧基以及多聚糖等化合物相对含量增加。 运用样地调查、生物量模型模拟和室内土壤样品分析方法，研究了次生林恢复和橡胶园建设对大气CO2的汇集作用。结果表明：退化土壤恢复为次生林、农田建设橡胶园能够有效促进植被和土壤中碳的汇集。次生林和橡胶林生物量增长速率分别为9.8，10.2 （9.4）t•ha-1•yr-1, 1 m表层土壤有机碳汇集速率分别为0.7和1.1 t•C•ha-1•yr-1。模拟结果显示，40年橡胶林生物量为327 (324) t•ha-1, 恢复50年后天然次生林生物量为395 t•ha-1。加之土壤有机碳，40年橡胶园约汇集碳190 t•ha-1, 次生林恢复50年碳汇集潜力为250 t•ha-1。

Composition deviation of arrays of FePt nanoparticles starting from poly(styrene)-poly(4-vinylpyridine) micelles

Ordered arrays of FePt nanoparticles were prepared using a diblock polymer micellar method combined with plasma treatment. Rutherford backscattering spectroscopy analyses reveal that the molar ratios of Fe to Pt in metal-salt-loaded micelles deviate from those when metal precursors are added, and that the plasma treatment processes have little influence upon the compositions of the resulting FePt nanoparticles. The results from Fourier transform infrared spectroscopy show that the maximum loadings of FeCl3 and H2PtCl6 inside poly( styrene)-poly(4-vinylpyridine) micelles are different. The composition deviation of FePt nanoparticles is attributed to the fact that one FeCl3 molecule coordinates with a single 4-vinylpyridine (4VP) unit, while two neighboring and uncomplexed 4VP units are required for one H2PtCl6 molecule. Additionally, we demonstrate that the center-to-center distances of the neighboring FePt nanoparticles can also be tuned by varying the drawing velocity.

Evolution of structural defects in SiOx films fabricated by electron cyclotron resonance plasma chemical vapour deposition upon annealing treatment

We study the structural defects in the SiOx film prepared by electron cyclotron resonance plasma chemical vapour deposition and annealing recovery evolution. The photoluminescence property is observed in the as-deposited and annealed samples. [-SiO3](2-) defects are the luminescence centres of the ultraviolet photoluminescence (PL) from the Fourier transform infrared spectroscopy and PL measurements. [-SiO3](2-) is observed by positron annihilation spectroscopy, and this defect can make the S parameters increase. After 1000 degrees C annealing, [-SiO3](2-) defects still exist in the films.

Preferential orientation growth of AIN thin films on Si (111) substrates by LP-MOCVD

Aluminum nitride (AIN) thin films were deposited on Si (111) substrates by low pressure metalorganic chemical vapor deposition system. The effects of the V/III ratios on the film structure and surface morphology were systematically studied. The chemical states and vibration modes of AIN films were characterized by X-ray photoelectron spectroscopy and Fourier transform infrared spectrometer. The optical absorption property of the AIN films, characterized by ultraviolet-visible-near infrared spectrophotometer, exhibited a sharp absorption near the wavelength of 206 mm. The AIN (002) preferential orientation growth was obtained at the V/III ratio of 10,000 and the preferential growth mechanism is presented in this paper according to the thermodynamics and kinetics process of the AIN growth.

The diphasic nc-Si/a-Si : H thin film with improved medium-range order

A series of silicon film samples were prepared by plasma enhanced chemical vapor deposition (PECVD) near the threshold from amorphous to nanocrystalline state by adjusting the plasma parameters and properly increasing the reactions between the hydrogen plasma and the growing surface. The microstucture of the films was studied by micro-Raman and Fourier transform infrared (FTIR) spectroscopy. The influences of the hydrogen dilution ratio of silane (R-H = [H-2]/[SiH4]) and the substrate temperature (T-s) on the microstructural and photoelectronic properties of silicon films were investigated in detail. With the increase of RH from 10 to 100, a notable improvement in the medium-range order (MRO) of the films was observed, and then the phase transition from amorphous to nanocrystalline phase occurred, which lead to the formation of diatomic hydrogen complex, H-2* and their congeries. With the increase of T-s from 150 to 275 degreesC, both the short-range order and the medium range order of the silicon films are obviously improved. The photoconductivity spectra and the light induced changes of the films show that the diphasic nc-Si/a-Si:H films with fine medium-range order present a broader light spectral response range in the longer wavelength and a lower degradation upon illumination than conventional a-Si:H films. (C) 2004 Elsevier B.V. All rights reserved.

Parameters determining crystallinity in beta-SiC thin films prepared by catalytic chemical vapor deposition

The effects of deposition gas pressure and H-2 dilution ratio (H-2/SiH4+CH4+H-2), generally considered two of dominant parameters determining crystallinity in beta-SiC thin films prepared by catalytic chemical vapor deposition (Cat-CVD), often called hot-wire CVD method, on the films properties have been systematically studied. As deposition gas pressure increase from 40 to 1000 Pa, the crystallinity of the films is improved. From the study of H-2 dilution ratio, it is considered that H-2 plays a role as etching gas and modulating the phases in beta-SiC thin films. On the basis of the study on the parameters, nanocrystalline beta-SiC films were successfully synthesized on Si substrate at a low temperature of 300degreesC. The Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) spectra show formation of beta-SiC. Moreover, according to Sherrer equation, the average grain size of the films estimated is in nanometer-size. (C) 2003 Elsevier B.V. All rights reserved.

Effects of crystalline quality on the phase stability of cubic boron nitride thin films under medium-energy ion irradiation

To investigate the effect of radiation damage on the stability and the compressive stress of cubic boron nitride (c-BN) thin films, c-BN films with various crystalline qualities prepared by dual beam ion assisted deposition were irradiated at room temperature with 300 keV Ar+ ions over a large fluence range up to 2 x 10(16) cm(-2). Fourier transform infrared spectroscopy (FTIR) data were taken before and after each irradiation step. The results show that the c-BN films with high crystallinity are significantly more resistant against medium-energy bombardment than those of lower crystalline quality. However, even for pure c-BN films without any sp(2)-bonded BN, there is a mechanism present, which causes the transformation from pure c-BN to h-BN or to an amorphous BN phase. Additional high resolution transmission electron microscopy (HRTEM) results support the conclusion from the FTIR data. For c-BN films with thickness smaller than the projected range of the bombarding Ar ions, complete stress relaxation was found for ion fluences approaching 4 x 10(15) cm(-2). This relaxation is accompanied, however, by a significant increase of the width of c-BN FTIR TO-line. This observation points to a build-up of disorder and/or a decreasing average grain size due to the bombardment. (c) 2005 Elsevier B.V. All rights reserved.

The study of high temperature annealing of a-SiC : H films

A series of amorphous silicon carbide films were prepared by plasma enhanced chemical vapor deposition technique on (100) silicon wafers by using methane, silane, and hydrogen as reactive resources. A very thin (around 15 A) gold film was evaporated on the half area of the aSiC:H films to investigate the metal induced crystallization effect. Then the a-SiC:H films were annealed at 1100 degrees C for 1 hour in the nitrogen atmosphere. Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to analyze the microstructure, composition and surface morphology of the films. The influences of the high temperature annealing on the microstructure of a-SiC:H film and the metal induced metallization were investigated.

Microstructure characterization of transition films from amorphous to nanocrocrystalline silicon

Hydrogenated silicon (Si:H) films near the threshold of crystallinity were prepared by very high-frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) using a wide range of hydrogen dilution R-H = [H-2]/[SiH4] values of 2-100. The effects of H dilution R-H on the structural properties of the films were investigated using micro-Raman scattering and Fourier transform infrared (FTIR) absorption spectroscopy. The obtained Raman spectra show that the H dilution leads to improvements in the short-range order and the medium-range order of the amorphous network and then to the morphological transition from amorphous to crystalline states. The onset of this transition locates between R-H = 30 and 40 in our case, and with further increasing R-H from 40 to 100, the nanocrystalline volume fraction increases from similar to23% to 43%, and correspondingly the crystallite size enlarges from similar to2.8 to 4.4 nm. The FTIR spectra exhibit that with R-H increasing, the relative intensities of both the SiH stretching mode component at 2100 cm(-1) and wagging mode component at 620 cm(-1) increase in the same manner. We assert that these variations in IR spectra should be associated with the formation of paracrystalline structures in the low H dilution films and nanocrystalline structures in the high H dilution films. (C) 2003 Elsevier Science B.V. All rights reserved.

Measurement of gain spectrum for Fabry-Perot semiconductor lasers by the Fourier transform method with a deconvolution process

To improve the accuracy of measured gain spectra, which is usually limited by the resolution of the optical spectrum analyzer (OSA), a deconvolution process based on the measured spectrum of a narrow linewidth semiconductor laser is applied in the Fourier transform method. The numerical simulation shows that practical gain spectra can be resumed by the Fourier transform method with the deconvolution process. Taking the OSA resolution to be 0.06, 0.1, and 0.2 nm, the gain-reflectivity product spectra with the difference of about 2% are obtained for a 1550-nm semiconductor laser with the cavity length of 720 pm. The spectra obtained by the Fourier transform method without the deconvolution process and the Hakki-Paoli method are presented and compared. The simulation also shows that the Fourier transform method has less sensitivity to noise than the Hakki-Paoli method.

Microstructure of a-SiOx : H

A set of a-SiOx:H (0.52 < x < 1.58) films are fabricated by plasma-enhanced-chemical-vapor-deposition (PECVD) method at the substrate temperature of 250degreesC. The microstructure and local bonding configurations of the films are investigated in detail using micro-Raman scattering, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). It is found that the films are structural inhomogeneous, with five phases of Si, Si2O:H, SiO:H, Si2O3:H and SiO2 that coexist. The phase of Si is composed of nonhydrogenated amorphous silicon (a-Si) clusters that are spatially isolated. The average size of the clusters decreases with the increasing oxygen concentration x in the films. The results indicate that the structure of the present films can be described by a multi-shell model, which suggests that a-Si cluster is surrounded in turn by the subshells Of Si2O:H, SiO:H, Si2O3:H, and SiO2.

Structural evaluation of polycrystalline silicon thin films by hot-wire-assisted PECVD

Tungsten wires were introduced into a plasma-enhanced chemical vapor deposition (PECVD) system as a catalyzer: we name this technique 'hot-wire-assisted PECVD' (HW-PECVD). Under constant deposition pressure (p(g)), gas flow ratio and catalyzer position, the effects of the hot wire temperature (T-f) on the structural properties of the poly-Si films have been characterized by X-ray diffraction (XRD), Raman scattering and Fourier-transform infrared (FTIR) spectroscopy. Compared with conventional PECVD, the grain size, crystalline volume fraction (X-e) and deposition rate were all enhanced when a high T-f was used. The best poly-Si film exhibits a preferential (220) orientation, with a full width at half-maximum (FWHM) of 0.2 degrees. The Si-Si TO peak of the Raman scattering spectrum is located at 519.8 cm(-1) with a FWHM of 7.1 cm(-1). The X-c is 0.93. These improvements are mainly the result of promotion of the dissociation of SiH4 and an increase in the atomic H concentration in the gas phase. (C) 2001 Elsevier Science B.V. All rights reserved.