Kinetics of photoinduced anisotropy in bacteriorhodopsin film under two pumping beams

Photoinduced anisotropy in bacteriorhodopsin (BR) film arises from the selective bleaching of BR molecules to linearly polarized light. The kinetics of photoinduced anisotropy excited by single and two pumping beams are investigated theoretically and experimentally. Compared with a single pumping beam (650 nm), which produces comparatively small photoinduced anisotropy, dual-wavelength linearly polarized pumping beams (650 and 405 nm) can obviously change the photoinduced anisotropy. When the polarization orientation of the 405 ran pumping beam is perpendicular to that of the 650 nm pumping beam, the peak and steady values of the photoinduced anisotropy kinetic curves are remarkably enhanced. But when the two pumping beams have parallel polarization orientation, the peak and steady values are restrained. At a fixed intensity of the 650 nm pumping beam, there exists an optimal intensity for the 405 nm pumping beam to maximize the value of the photoinduced anisotropy. The photoinduced transmittance of the polarizer-BR-analyzer system is modulated by the polarization angle of the 405 nm pumping beam in an approximate-cosine form. (C) 2008 Optical Society of America.

Application of bacteriorhodopsin film for polarization phase-shifting interferometry

Photoinduced anisotropy in bacteriorhodopsin (BR) film is based on photoanisotropic selective bleaching of BR molecules under linearly polarized excitation light. It is modulated by the polarization orientation of the linearly polarized light. The anisotropic information recorded in the BR film is read by a circularly polarized light, which is in turn converted into an elliptical polarized light by the BR film. The rotation angle and the ellipticity of the elliptical polarized light are dependent on the polarization orientation of the linearly polarized excitation light. A phase-shifting interferometer based on the photoinduced anisotropy of BR film is presented theoretically and experimentally. Phase shift is controlled by the polarization orientation of the external excitation light, thus, the phase shift can be controlled without moving parts inside the interferometer, which contributes to the mechanical stability of the system.

Langmuir-Blodgett 薄膜诱导晶体生长研究

近年来，Langmuir—Blodgett（LB）薄膜诱导晶体生长的方法引起了人们的极大关注。通过优化LB膜的结构和化学性质可以调控晶体的结构、形貌、取向、晶型。本论文在此领域的主要研究内容如下： (1) 制备了硬脂酸和十八胺两种具有不同结构和官能团的LB膜，然后把这两种膜垂直浸入到中性的甘氨酸溶液中。实验结果表明用不同结构和化学性质的LB膜不仅可以调控晶体的结构、形貌和取向，并且可以在相同的溶液中诱导出不同晶型的晶体。 (2) 制备了Y型硬脂酸LB膜，然后把这种模板以不同的方式浸入到氯化钾溶液中。通过改变LB膜模板在溶液中的放置方式，控制溶液中的诱导成核和自发成核的过程，从而生成不同形貌的氯化钾晶体。 (3)我们研究了不同热力学状态的LB膜诱导五水硫酸铜晶体生长过程。结果表明LB膜即使在液态状态下，仍有诱导晶体生长的能力。且LB膜的热力学状态对晶体的形貌和取向有很大的影响。 另外，我们在以上工作之外，还作了两项其他工作。 (4) 研究了各种羧酸类（甲酸、乙酸、丙酸）、丙酮、醇类（甲醇、乙醇、丙醇、丁醇）对谷氨酸溶液结晶晶型的影响。结果表明：当70°C的谷氨酸饱和溶液快速冷却搅拌到0°C时，有羧酸类物质存在时可以得到β型晶体;而当有酮类、醇类、或无添加剂时在相同条件下得到α型晶体。 (5) 利用LB技术制备了聚苯乙烯和硬脂酸的混合薄膜。实验结果证明PS和SA在混合LB膜中是相分离的。其过程是PS在空气/水界面上首先发生聚集,然后这种聚集的程度随着膜压的增加而增大.并且PS在空气-LB膜界面上在空气/LB膜界面上的聚集程度随着时间仍继续发生改变。

十八胺及其相关物质Langmuir-Blodgett膜的制备和性质研究

Langmuir-Blodgett（LB）膜技术由于在电子学、非线性光学以及化学传感器等领域具有潜在的应用前景而引起了人们的研究兴趣，其中它的热稳定性对LB膜的应用领域和范围具有一定的影响。本论文在此领域的主要研究内容如下： 利用LB膜技术分别制备了十八胺及硬脂酸、氘代硬脂酸的多层LB膜，采用变温傅立叶变换红外光谱研究了三种LB膜的相变行为。实验发现：十八胺LB膜在55-75 oC温度区间内发生相变，其CH2对称和反对称伸缩振动频率向高能量区发生明显移动；硬脂酸LB膜在70-80 oC的温度区间内发生了明显的相转变，CH2对称和反对称伸缩振动的强度比在升温过程中也有显著改变；氘代硬脂酸LB膜的相行为发生在65-70 oC的温度区间内。 利用LB膜技术制备了十八铵硬脂酸盐(C18H37NH3+C17H35COO-, ODASA)与十八铵氘代硬脂酸盐(C18H37NH3+C17D35COO-, ODASA-d35) Langmuir-Blodgett (LB)膜，使用变温傅立叶变换红外透射光谱研究了它们的热行为。发现LB膜中十八铵硬脂酸盐分子的两个碳氢链高度有序，然而在十八铵氘代硬脂酸盐LB分子中的来自于十八胺的碳氢链部分无序，即在常温下有一些扭曲构象存在于碳氢链中。而十八铵硬脂酸盐的热稳定性也与十八铵氘代硬脂酸盐的热稳定性有些不同。在十八铵硬脂酸盐LB膜中，碳氢链在85 oC到90 oC的温度区间内发生非常明显的有序-无序变化。而在十八铵氘代硬脂酸盐LB膜中，碳氢链和来自于硬脂酸的氘代的烃链各自呈现出不同的热行为，即：碳氢链在80-90 oC的温度区间发生有序-无序变化，尤其是在80-85 oC的温度范围内这个变化非常显著；而氘代的烃链则在70 oC到85 oC这个较长的温度区间发生缓慢的相变。 分别制备了十八铵十二酸盐 （C18H37NH3+C11H23COO-，ODALA）和十八铵二十四酸盐（C18H37NH3+C23H45COO-,ODATA）LB膜，并用变温傅立叶变换红外透射光谱法研究了十八铵十二酸盐和十八铵二十四酸盐LB膜的热行为，比较了十八铵十二酸盐、十八铵硬脂酸盐和十八铵二十四酸盐这三种双链化合物LB膜的热行为。温度相关的红外光谱显示，这三种物质LB膜的热稳定性取决于碳链的长度。其中，十八铵十二酸盐LB膜在50-65 oC的温度区间内发生相变。对应的，十八铵二十四酸盐LB膜在80-90 oC的温度范围内发生有序-无序变化。令人感兴趣的是，十八铵二十四酸盐LB膜的相变温度与十八铵硬脂酸盐LB膜的相变温度基本一样，都是80-90 oC，也即在十八铵二十四酸盐和十八铵硬脂酸盐两种LB膜中，即使二十四酸取代了硬脂酸对前者的热稳定性的影响非常小。以上结果说明，在双长链化合物中，有效链长度取决于双链中的较短的那个烃链，从而来决定膜的热稳定性。在十八铵二十四酸盐LB膜中，十八胺的全部碳链对膜的热稳定性有贡献，而二十四酸的碳链则只有部分（有效部分）烃链有贡献。 制备了十八胺单层和多层LB膜和粒径为几个纳米的金纳米粒子。由于十八胺在pH值小于10.3的溶液中氨基带正电荷，使其置于金纳米溶胶中，利用带正电荷的十八胺和附着负电荷的金纳米粒子之间的静电作用，使得金纳米颗粒成功地吸附组装到十八胺的有序分子膜中，形成有规律的纳米颗粒层。通过紫外-可见光谱、红外光谱以及扫描电镜观察到，金纳米颗粒通过这种方法能够很好的组装在有机分子膜上，而且由于十八胺LB膜的高度有序性使得金纳米颗粒的组装层有序。而且，不同层数的十八胺LB膜对金纳米粒子呈现出不同的吸附行为。 测量了含微量甲醇（体积分数为0.04%~0.24%）的系列乙醇水溶液的近红外光谱，利用近红外光谱分析建立了预测甲醇含量的定量分析模型。比较了用外部检验法（Test Set-Validation）和交叉检验法(Cross-Validaton)建立的数学模型以及研究了使用外部检验法时校正集和检验集样品数的改变对模型预测结果的影响。结果发现，当校正集样品数为15检验集样品数为6（总样品数为21）时，使用外部检验法建立的数学模型预测结果较好，外部检验与交叉检验的预测均方根误差（分别为RMSEE和RMSEP）都较小（分别为0.0105和0.0115）而且很接近。结果表明，近红外光谱方法简单，准确而且实用。

Evaluation of both composition and strain distributions in InGaN epitaxial film using x-ray diffraction techniques

The composition and stain distributions in the InGaN epitaxial films are jointly measured by employing various x-ray diffraction (XRD) techniques, including out-of-plane XRD at special planes, in-plane grazing incidence XRD, and reciprocal space mapping (RSM). It is confirmed that the measurement of (204) reflection allows a rapid access to estimate the composition without considering the influence of biaxial strain. The two-dimensional RSM checks composition and degree of strain relaxation jointly, revealing an inhomogeneous strain distribution profile along the growth direction. As the film thickness increases from 100 nm to 450 nm, the strain status of InGaN films gradually transfers from almost fully strained to fully relaxed state and then more in atoms incorporate into the film, while the near-interface region of InGaN films remains pseudomorphic to GaN.

CHANNELING ALIGNMENT FOR EPITAXIAL LIGHT-MASS FILM ON HEAVY-MASS SUBSTRATE

A simple procedure for obtaining a background-free backscattering spectrum of a light-mass film on a heavy-mass substrate by a normal incidence/grazing exit geometry has been described. Using this method such films can be aligned rapidly and accurately, and the impurity or defect information on the films can be obtained without need for realignment. Example is given from MeV Li-3+ analysis of a deposited film of Si on a single crystal substrate of yttria-stabilized, cubic zirconia.

EFFECT OF SURFACE-STRUCTURES UPON ULTRATHIN-FILM INTERFERENCE-FRINGES

Effect of surface structures upon ultrathin film interference fringes generated from extremely thin films or epitaxial layers grown on semiconductor wafers has been studied. Since dark regions of fringes correspond to the places where the thin films are destroyed or absent, the fringes are investigated to detect uneven surfaces with undesired structures. Therefore, surface microstructures can be detected and characterized effectively by the modification of the fringes.

EFFECT OF TOTAL HYDROGEN CONTENT IN SILICON-NITRIDE SENSITIVE FILM ON PERFORMANCE OF ISFET

Quantitative determinations of the hydrogen content and its profile in silicon nitride sensitive films by the method of resonant nuclear reaction have been carried out. At a deposition temperature of 825-degrees-C, hydrogen exists in an LPCVD silicon nitride sensitive film and the hydrogen content on its surface is in the range (8-16) x 10(21) cm-3, depending on the different deposition processes used. This hydrogen content is larger than the (2-3) x 10(21) cm-3 in its interior part, which is homogeneous. Meanwhile, we observe separate peaks for the chemical bonding configurations of Si-H and N-H bonds, indicated by the infrared absorption bands Si-O (1106 cm-1), N-H (1200 cm-1), Si-H-3 (2258 cm-1) and N-H-2 (3349 cm-1), respectively. The worse linear range of the ISFET is caused by the presence of oxygen on the surface of the silicon nitride sensitive film. The existence of chemical bonding configurations of Si-H, N-H and N-Si on its surfaces is favourable for its pH response.

EFFECT OF A SI LAYER ON THE SUPERCONDUCTIVE PROPERTIES OF A BIPBSRCACUO THIN-FILM

The Pb-doped BiSrCaCuO superconducting films were grown by the single source mixed evaporation technique. The microbridges of dimensions 50 mum x 40 mum were fabricated by standard photolithography technologies. Si films with a thickness of 2500 angstrom were deposited on the microbridge area surfaces of BiPbSrCaCuO superconducting films by rf-magnetron sputtering. A greatly lowered zero resistance temperature of the microbridge area of the BiPbSrCaCuO film after Si sputtering was found. A non-linear effect of the current-voltage (I-V) characteristics at 78 K was shown. The high-frequency capacitance-voltage (C-V) curve of this structure at 78 K was symmetrical with the maximum capacitance at V = 0, and the capacitance decreased with increasing applied bias voltage. Afl experimental results are discussed.