激光照射下金电极/溶液界面的电子转移行为

用伏安法初步研究了激光照射下金电极／溶液界面的电子转移行为。对Ｆｅ＾３＋／Ｆｅ＾２＋,激光照射引起氧化还原峰增高并向阳极方向移动,氧化还原电位负向变化,激光功率对电流－电位曲线的平移幅度具有明显影响。激光照射对抗坏血酸的电子转移作用更显著,电流峰高增加了２．０２倍,过电位减少了０．２５Ｖ。激光能量对电极表面的作用及界面溶液层的影响加速了电子转移并提高了电极反应的灵敏度。     

Electrical characterization of current conduction in Au/TiO2/n-Si at wide temperature range

In this study, we have examined Au/TiO₂/n-Si Schottky barrier diodes (SBDs), in order to interpret in detail the experimental observed non-ideal current–voltage–temperature (I–V–T) characteristics. I–V characteristics were measured in the wide temperature range of 80–400 K. TiO₂ was deposited on n-Si substrate by reactive magnetron sputtering. The zero-bias barrier height (ϕ_B0) and ideality factor (n) show strong temperature dependence. While n decreases, ϕ_B0 increases with increasing temperature. Experimental results show that the current across the SBDs may be greatly influenced by the existence of Schottky barrier height (SBH) inhomogeneity. These temperature behaviors have been explained on the basis of the thermionic emission (TE) theory with Gaussian distribution (GD) of the barrier heights (BHs) due to BH inhomogeneities at metal–semiconductor (M/S) interface. From this assumptions, obtaining Richardson constant value of the A^* 121.01 A/cm² K² is perfect agreement with the theoretical value of 120 A/cm² K² for n-type Si. Hence, behaviors of the forward-bias I–V characteristics of the Au/TiO₂/n-Si (SBDs) can be successfully explained on the basis of a TE mechanism with a double Gaussian distribution of the BHs.     

3-D/2-D registration by integrating 2-D information in 3-D

In image-guided therapy, high-quality preoperative images serve for planning and simulation, and intraoperatively as "background", onto which models of surgical instruments or radiation beams are projected. The link between a preoperative image and intraoperative physical space of the patient is established by image-to-patient registration. In this paper, we present a novel 3-D/2-D registration method. First, a 3-D image is reconstructed from a few 2-D X-ray images and next, the preoperative 3-D image is brought into the best possible spatial correspondence with the reconstructed image by optimizing a similarity measure (SM). Because the quality of the reconstructed image is generally low, we introduce a novel SM, which is able to cope with low image quality as well as with different imaging modalities. The novel 3-D/2-D registration method has been evaluated and compared to the gradient-based method (GBM) using standardized evaluation methodology and publicly available 3-D computed tomography (CT), 3-D rotational X-ray (3DRX), and magnetic resonance (MR) and 2-D X-ray images of two spine phantoms, for which gold standard registrations were known. For each of the 3DRX, CT, or MR images and each set of X-ray images, 1600 registrations were performed from starting positions, defined as the mean target registration error (mTRE), randomly generated and uniformly distributed in the interval of 0-20 mm around the gold standard. The capture range was defined as the distance from gold standard for which the final TRE was less than 2 mm in at least 95% of all cases. In terms of success rate, as the function of initial misalignment and capture range the proposed method outperformed the GBM. TREs of the novel method and the GBM were approximately the same. For the registration of 3DRX and CT images to X-ray images as few as 2-3 X-ray views were sufficient to obtain approximately 0.4 mm TREs, 7-9 mm capture range, and 80%-90% of successful registrations. To obtain similar results for MR to X-ray registrations, an image, reconstructed from at least 11 X-ray images was required. Reconstructions from more than 11 images had no effect on the registration results.     

TEM and HAADF-STEM study of a Au catalyst supported on a TiO2 nano-rod

Gold nanoparticles were deposited on TiO2 nano-rods by a deposition precipitation method. This Au/TiO2 nano-rods catalyst is active for CO oxidation even at temperatures less than 273K and is as active as the catalyst of Au supported on conventional TiO2 particles. Transmission electron microscopy (TEM) showed that the TiO2 nano-rods were composed of a single anatase crystal and had a pillar shape with an axis along the <111> direction surrounded by flat four [101] planes. High angle annular dark field scanning TEM (HAADF-STEM) also revealed that a Au platelet with a thickness of 0.5-1 nm was formed at the interface between TiO2 nano-rods. The Au platelet was not observed when conventional round particles of TiO2 were used as a support.     

Magneto-optical behaviors at a 2-D ferromagnetic/organic semiconductor interface for singlet fission

This article reports the magneto-optical effects on the singlet fission of the p-type organic semiconductor, tetracene, from a ferromagnetic/semiconductor interface between thin films of cobalt and tetracene. We experimentally show that this interface has two effects on the thin films of tetracene: spin interactions and electrical polarization. The experimental tools used to study the interface include magnetic field effect photoluminescence (MFE_PL), photoluminescence and absorption. Spin interaction effects are shown by MFE_PL data, where we observe a large increase in the maximum MFE_PL when cobalt is introduced, as well as changes in the hyperfine interactions at low magnetic fields. Electrical polarization is analyzed with photoluminescence and absorption measurements, showing small changes in the energy difference between the HOMO and LUMO levels of tetracene, as well as an increase in the electron-phonon coupling in tetracene. Also, electrical polarization is shown to increase electrical interactions between tetracene molecules. Therefore, we conclude that using spin interactions and electrical polarization from the ferromagnetic/organic semiconductor interface can tune the properties of tetracene, ultimately enhancing singlet fission. This work gives new insight to understand the singlet fission process using a ferromagnetic interface. These changes can be further utilized in photovoltaic applications based on this singlet fission material and be applied to other similar types of singlet fission organic semiconductors.     

三维全屏幕象差特性的研究

从全息屏幕对投影物镜出瞳象(即视觉区域)的形成及该出瞳象对高斯象的偏离出发,研究了三维全息屏幕的象差特性。     

Interdiffusion of the p-InP with Au−Zn,Ti/Au,Pd/Au,Ti/Pd/Au at interface and their electrical properties

 In this report,the interdiffusion between the p-InP with Au-Zn,Ti/Au,Pd/Au and Ti/Pd/Au at interface have been investigated by Auger electron spectroscopy and electron spectroscopy for chemical analysis.The surface morphology for the heat treatment are observed with scanning electron microscopy. It is found that the indiffusion of Au is easier than that of Pd and Ti and the outdiffusion of In is easier than that of P.The combination state of In and Au is formed during the heat treatment of p-InP/Au-Zn. The effects of the alloying temperature and time on the specific contacts resistance of p-InP/Au-Zn system are studided.The low specific contact resistance,p_c=2.4-2.7×10~(-4)Ω-cm~2,is obtained when alloying at 450℃ for 2 min or at 350℃ for 30 min. These results indicate that the specific contact resistance strongly depend on the“interdiffusion degree”.The Zn in Au-Zn ahoy distributes onto the most surface layer of p-InP/Au-Zn system during evaporation process and heat treatment.It may be one of the reasons for the higher specific contacts resistance.     

Ultrafast Plasmonic Hot Electron Transfer in Au Nanoantenna/MoS2 Heterostructures

2D transition metal dichalcogenides are becoming attractive materials for novel photoelectric and photovoltaic applications due to their excellent optoelectric properties and accessible optical bandgap in the near‐infrared to visible range. Devices utilizing 2D materials integrated with metal nanostructures have recently emerged as efficient schemes for hot electron‐based photodetection. Metal‐semiconductor heterostructures with low cost, simple procedure, and fast response time are crucial for the practical applications of optoelectric devices. In this paper, template‐based sputtering method is used first to fabricate Au nanoantenna (NA)/MoS₂ heterostructures with low cost, simple preparation, broad spectral response, and fast response time. Through the measurement of femtosecond pump‐probe spectroscopy, it is demonstrated that plasmon‐induced hot electron transfer takes place in the Au NA/MoS₂ heterostructure on the order of 200 fs with an injected electron density of about 5.6 × 10¹² cm^?2. Moreover, the pump‐power‐dependent photoluminescence spectra confirm that the exciton energy of MoS₂ can be enhanced, coupled, and reradiated by the Au NA. Such ultrafast plasmon‐induced hot electron transfer in the metal‐semiconductor heterostructure can enable novel 2D devices for light harvesting and photoelectric conversion.     

Realizations of fast 2-D/3-D image filtering and enhancement

This paper proposes a novel algorithm for multidimensional image enhancement based on a fuzzy domain enhancement method, and an implementation of a recursive and separable low-pass filter. Considering a smoothed image as a fuzzy data set, each pixel in an image is processed independently, using fuzzy domain transformation and enhancement of both the dynamic range and the local gray level variations. The algorithm has the advantages of being fast and adaptive, so it can be used in real-time image processing applications and for multidimensional data with low computational cost. It also has the ability to reduce noise and unwanted background that may affect the visualization quality of two-dimensional (2-D)/three-dimensional (3-D) data. Examples for the applications of the algorithm are given for mammograms, ultrasound 3-D images, and photographic images.     

New wire interface for graded 3-D TLM

A new 3-D graded TLM model for thin radiating wires is presented. The model differs from previous TLM models because the wire is modelled at the interfaces between cells, rather than through the centre of the node. The connection between the TLM symmetrical condensed-node link lines and the line forms a 'wire interface'. The scattering algorithm for the interface and simulation results are given.<>     

Enhanced Photocatalytic Activity of Au/TiO2 Nanocomposite Prepared Using Bifunctional Bridging Linker

Using a simple bifunctional bridging linker, nanosized gold and titanium dioxide composites are prepared containing different Au loadings. Linker is synthesized to contain both catechol and thiol moieties to enable binding to the TiO₂ and Au surface respectively. Au/TiO₂ nanocomposites are prepared using simple synthetic route that allows the control over the amount of Au nanoparticles, a property which plays a significant role in the catalytic activity of hybrid materials. Photocatalytic activity of materials prepared using different TiO₂ precursors is investigated using reactive oxygen species sensitive assay based on activation of horseradish peroxidase (HRP) enzyme. Significant increase in catalytic activity is observed for all Au/TiO₂ nanocomposites with Au/TiO₂ prepared by use of the bridging linker being up to 5.5 times more active than bare commercial TiO₂ nanoparticles. In addition to 365 nm light excitation, less energetic 470 nm light, which is more suitable for the use with biological systems, is used to induce photocatalytic activity. Finally, prepared photocatalytic materials are successfully used to exert temporal control over enzymatic activity, a feature which is important for the study of both enzymatic activity and design of novel bio‐sensing platforms.     

Gradient-based 2-D/3-D rigid registration of fluoroscopic X-ray to CT

We present a gradient-based method for rigid registration of a patient preoperative computed tomography (CT) to its intraoperative situation with a few fluoroscopic X-ray images obtained with a tracked C-arm. The method is noninvasive, anatomy-based, requires simple user interaction, and includes validation. It is generic and easily customizable for a variety of routine clinical uses in orthopaedic surgery. Gradient-based registration consists of three steps: 1) initial pose estimation; 2) coarse geometry-based registration on bone contours, and; 3) fine gradient projection registration (GPR) on edge pixels. It optimizes speed, accuracy, and robustness. Its novelty resides in using volume gradients to eliminate outliers and foreign objects in the fluoroscopic X-ray images, in speeding up computation, and in achieving higher accuracy. It overcomes the drawbacks of intensity-based methods, which are slow and have a limited convergence range, and of geometry-based methods, which depend on the image segmentation quality. Our simulated, in vitro, and cadaver experiments on a human pelvis CT, dry vertebra, dry femur, fresh lamb hip, and human pelvis under realistic conditions show a mean 0.5-1.7 mm (0.5-2.6 mm maximum) target registration accuracy.     

3-D/2-D registration of CT and MR to X-ray images

A crucial part of image-guided therapy is registration of preoperative and intraoperative images, by which the precise position and orientation of the patient's anatomy is determined in three dimensions. This paper presents a novel approach to register three-dimensional (3-D) computed tomography (CT) or magnetic resonance (MR) images to one or more two-dimensional (2-D) X-ray images. The registration is based solely on the information present in 2-D and 3-D images. It does not require fiducial markers, intraoperative X-ray image segmentation, or timely construction of digitally reconstructed radiographs. The originality of the approach is in using normals to bone surfaces, preoperatively defined in 3-D MR or CT data, and gradients of intraoperative X-ray images at locations defined by the X-ray source and 3-D surface points. The registration is concerned with finding the rigid transformation of a CT or MR volume, which provides the best match between surface normals and back projected gradients, considering their amplitudes and orientations. We have thoroughly validated our registration method by using MR, CT, and X-ray images of a cadaveric lumbar spine phantom for which "gold standard" registration was established by means of fiducial markers, and its accuracy assessed by target registration error. Volumes of interest, containing single vertebrae L1-L5, were registered to different pairs of X-ray images from different starting positions, chosen randomly and uniformly around the "gold standard" position. CT/X-ray (MR/ X-ray) registration, which is fast, was successful in more than 91% (82% except for L1) of trials if started from the "gold standard" translated or rotated for less than 6 mm or 17 degrees (3 mm or 8.6 degrees), respectively. Root-mean-square target registration errors were below 0.5 mm for the CT to X-ray registration and below 1.4 mm for MR to X-ray registration.     

On the transformation of the potential barrier at a GaAs/Au interface during heat treatment

The effect of vacuum heat treatment on the electronic state of a GaAs(100) surface coated with island layer of gold is investigated. It is found that the effective band bending in the depletion layer decreases monotonically with increasing anneal temperature in the range 100–500 °C. The Fermi level at the surface remains approximately 0.8 eV below the conduction-band bottom. The transformation of the potential barrier is due to the formation of a strongly doped region near the surface with high tunneling transmittance. It is shown that the photoelectric properties of thin GaAs films can be controlled by adsorption of gold and heat treatment. Fiz. Tekh. Poluprovodn. 33, 1350–1354 (November 1999)     

1维全息光子晶体的偏振特性

为了研究两种偏振光通过1维光子晶体的偏振特性,采用传输矩阵法做了相关计算,得到介质折射率、折射率调制的变化,在光正入射和倾斜入射时对不同偏振光的禁带都有影响的结果。结果表明,当光线正入射的时候,折射率和折射率调制的变化都不会影响禁带位置,折射率增大,禁带宽度减小;折射率调制增大,禁带宽度变大,正入射时p偏振、s偏振的禁带完全重合;当光线以一定的角度照射到介质表面上时,两种偏振态下禁带位置随折射率调制的增大移向低频,带的中心位置一样,禁带宽度变大。两种偏振态下禁带带宽随折射率的增大变窄,禁带中心移向低频,s偏振的带宽减小得更明显;介质厚度对不同偏振态下禁带没有任何影响。这为设计1维全息光子晶体偏振片提供了理论依据。     

Al2O3/Al复合材料界面上MgAl2O4尖晶石形成的高分辨电镜观察

界面问题一直是复合材料研究者最关心的话题之一.界面结合的好坏直接关系到载荷从基体向增强体的传递效率.Al2O3/Al复合材料中,由于Al与Al2O3本征不润湿的特征,人们提出了一系列的措施来改良界面,其中一种就是基体合金化.Mg元素是显著增强润湿的合金元素之一,但是由于Mg在界面上引起的一系列化学反应使其界面反应润湿现象变得复杂起来.     

利用金作为催化剂在不同衬底上制备二氧化硅纳米线

利用金作为催化剂分别在二氧化硅及硅衬底上制备出二氧化硅纳米线。用扫描电子显微镜（SEM）及x射线光电子能谱（XPS）对纳米线进行了结构表征。SEM结果表明二氧化硅纳米线的长度为几个纳米,直径为20-150纳米。XPS结果给出硅与氧的原子比为1:2,说明所得到的为二氧化硅纳米线。二氧化硅纳米线的生长机理为气-液-固（VLS）机制。实验发现退火时间影响二氧化硅纳米线的形貌。我们也讨论了衬底对纳米线生长的影响。     

Electrical and interface properties of Au/DNA/n-Si organic-on-inorganic structures

The effect of the thickness and coverage rate of a DNA film on the electrical and interface properties of Au/DNA/n-Si organic-on-inorganic structures has been investigated. The thin film properties of the DNA deposited on n-Si wafer were characterized by atomic force microscopy. The effect of the thickness and coverage rate of the DNA layer was investigated by evaluating electrical parameters, such as the barrier height, ideality factor, series resistance, and interface state density. The thickness and coverage rate of the DNA layer significantly affects the electrical properties of the Au/DNA/n-Si organic-on-inorganic structures. The interface state density properties of the Au/DNA/n-Si diodes were determined by conductance technique. The results show that the interface state density decreases with decrease in both film thickness and coverage rate of the DNA in an acetate buffer, modifying the electronic parameters of the Au/DNA/n-Si diodes.     

Capturing transiently charged states at the C60/TiO2(110) interface by time-resolved soft X-ray photoelectron spectroscopy

Time-resolved soft X-ray photoelectron spectroscopy is utilized to determine an energy level alignment and the photoexcited carrier dynamics at a C₆₀/TiO₂(110) interface. The interface electronic structure is characterized by a type II junction, which favors an injection of photoexcited electrons from C₆₀ to TiO₂. Ultraviolet (UV) laser pulse irradiation induces transient shifts of both C 1s and Ti 2p core levels towards the higher binding energies. These energy shifts are caused by a laser-induced charge transfer between the C₆₀ layer and the TiO₂(110) surface. Upon UV absorption, valence electrons of C₆₀ are promoted to unoccupied levels, followed by a resonant transfer to TiO₂, leaving C₆₀ in a cationized state. On the TiO₂(110) side, the electrons are injected into the conduction band to raise the carrier density so that downward bending of the TiO₂ band is induced. The UV-excited states of C₆₀ and TiO₂ have sufficiently longer lifetime than the lifetime of the electron–hole pairs in solid C₆₀. The C₆₀/TiO₂(110) interface is, thus, proved to be efficient for separating the electron–hole pairs generated within the C₆₀ layer.