Whispering-gallery modes in glass microspheres: optimization of pumping in a modified confocal microscope

Whispering-gallery modes (WGMs) on Nd3+-doped glass microspheres with a radius of ～15?μm were measured in a modified confocal microscope, where a dual spatial resolution in both excitation and detection zones was possible. As an alternative to the standard excitation mechanism by an evanescent wave, we used an efficient pumping/detecting scheme, focusing a laser in the microsphere and exciting the Nd3+ ions, whose fluorescent emission produces the WGMs. We have also measured the generated WGMs by changing the detection zone, where higher amplitude resonances were found when exciting in the center and detecting at the edge of the microsphere.     

Track sensitivity and the surface roughness measurements of CR-39 with atomic force microscope

Atomic Force Microscope (AFM) has been applied to evaluate the surface roughness and the track sensitivity of CR-39 track detector. We experimentally confirmed the inverse correlation between the track sensitivity and the roughness of the detector surface after etching. The surface of CR-39 (CR-39 doped with antioxidant (HARZLAS (TD-1)) and copolymer of CR-39/NIPAAm (TNF-1)) with high sensitivity becomes rough by the etching, while the pure CR-39 (BARYOTRAK) with low sensitivity keeps its original surface clarity even for the long etching.     

腐蚀时间对蓝宝石衬底上外延生长GaN质量的影响

使用熔融的KOH在高温下对c面蓝宝石衬底进行不同时间的腐蚀,借助扫描电镜、原子力显微镜对衬底表面进行了表征,然后利用金属有机物化学气相沉积设备在不同腐蚀时间的衬底样品上进行了GaN材料的外延生长。通过X射线衍射结果比较了两组衬底上外延材料的质量,利用原子力显微镜结果对外延层表面形貌进行了分析,最后论述了腐蚀时间的调整对蓝宝石衬底上外延生长氮化镓质量的影响机理。     

甲壳胺膜中MS(M=Cd,Zn)半导体纳米微粒形成机理的探讨

采用红外光谱（ＩＲ）和原子力显微镜（ＡＦＭ）对甲壳胺中纳米微晶生长过程进行了监测,并对测试结果进行了分析与讨论,提出甲壳胺膜中ＭＳ（Ｍ＝Ｃｄ,Ｚｎ）半导体纳米微晶可能的生长机制。同时还利用ＡＦＭ对甲壳胺中纳米微晶的形貌和尺度进行了测定。     

The evanescent-wave cavity ring-down spectroscopy technique applied to the investigation of thermally grown oxides on Si(100)

We report about the contribution of thermally grown SiO_x overlayer on the SiO_x/Si interface (with oxidation states Siⁿ⁺, where n = 1, 2, 3, 4) to the optical losses of a resonant spectroscopic cavity. The experiments on Si oxide thin films were performed in evanescent wave for Si samples in contact with a total internal reflection surface of a BK7 prism. The evanescent field can be exploited to investigate properties and processes such as the absorption of thin film or solid/air interface reactions. The results show that the oxide overlayer thickness grows with the thermal exposure time and is limited after more than 7 h of treatment. Transmission electron microscopy has been used for the native oxide thickness measurement and angle-resolved X-ray photoelectron spectroscopy used to determine the thermal oxide thickness. A change of absorption coefficient Δα in the range 100–200 cm^?1 is obtained by evanescent-wave cavity ring-down spectroscopy (EW-CRDS) for thermal silicon oxide overlayer, in agreement with the general trend from literature. The evaluation from the EW-CRDS experiments presents the used setup as a competitive method for measuring the absorption properties of thin overlayer.     

Surface roughness analysis and magnetic property studies of nickel thin films electrodeposited onto rotating disc electrodes

Ni films were electrodeposited onto polycrystalline gold substrates mounted on a rotating disc electrode. The effects of rotation speed, film thickness and current density on the kinetic roughening and magnetic properties of the films were investigated. The film surface roughness was imaged using an atomic force microscope (AFM). The results indicate that the film roughness increases as the film thickness or deposition current density increases. We found that the electrodeposited Ni films exhibit anomalous scaling since both local and large-scale roughnesses show a power-law dependence on the film thickness. The effect of electrode rotation speed on the film surface roughness was also investigated. Scanning electron microscopy studies (SEM) had a good agreement with the AFM results. The average crystalline size of the film surfaces is also calculated from X-ray line broadening using (220) peak and Debye–Scherrer formula. The obtained results agree with that of AFM and SEM. The Ni thin films which are grown at different deposition current densities and rotation speeds exhibit in-plane magnetization with coercivities less than 110 Oe.     

Influence of surface preparation on CdZnTe nuclear radiation detectors

High resolution X-ray diffraction (HRXRD), Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM) techniques were used to characterize the surface of CdZnTe (CZT) samples treated by mechanical lapping, polishing and chemical etching processes. The results confirm that the etching process produces the highest intensity diffraction peak, and the best full-width-at-half-maximum (FWHM). Fourier Transform Infrared (FTIR) spectroscopy shows that fine polishing increases the infrared transmission of the CZT sample, while etching with 2% bromine methanol (BM) etching decreases the infrared transmission. Different etchants and concentrations were investigated by comparing the surface morphology and roughness. The bromine methanol etching has shown more flat surface with lower roughness than the other etchants.     

基于整体柱的超灵敏表面增强拉曼检测

本文提出了一种全新的基于整体柱材料的SERS检测方法。通过将探针分子和银溶胶混合后滴加在整体柱上, 我们可以得到浓度低至10-18 mol/L的罗丹明6G(R6G)及10-16 mol/L的对巯基苯胺(PATP)的SERS信号。利用原子力显微镜(AFM)和扫描电镜(SEM)对银溶胶及整体柱材料进行了表征。通过实验结果可以初步推测, 整体柱材料的表面形态和孔结构可以促进银溶胶产生“热点”。     

Nonlinear absorption properties correlated with the surface and structural changes of ultra short pulse laser irradiated CR-39

We have investigated femtosecond laser irradiation effects on the surface topography, structural changes and nonlinear absorption properties of CR-39. For this purpose, a CR-39 target was exposed in air to 25 fs, 800 nm Ti: sapphire laser radiation at fluences ranging from 0.25 J cm⁻² to 3.6 J cm⁻². The surface of irradiated CR-39 probed by an Atomic Force Microscope (AFM) exhibits the formation of several topographical structures, like bumps, explosions and nano cavities. Raman spectroscopy is performed to explore chemical and structural modification of the irradiated target. The spectroscopy reveals changes such as cross linking, bond breaking, formation of new bonds etc. in the fundamental structure of the polymer after irradiation. In order to establish a correlation between morphological and structural changes with the changes in the nonlinear absorption of the irradiated CR-39, a Z-scan technique was employed. A comparison of experimentally obtained data from Z-scan measurements with our calculations predicts the dominance of three-photon absorption in the case of pristine CR-39, whereas for irradiated targets concurrence of three- and two-photon absorption is probable. Nonlinear absorption increases with increasing laser fluences and is well correlated by surface and structural changes revealed by AFM and Raman spectroscopy.     

PI/AlO（OH）-SiO2纳米杂化薄膜的制备及电性能分析

以聚酰亚胺作为高聚物反应基体,通过正硅酸乙酯（TEOS）和异丙醇铝的水解缩合反应,使之和聚酰亚胺发生溶胶凝胶反应,从而制备出AlO （OH）/SiO2不同比例的聚酰亚胺杂化薄膜.通过利用原子力显微镜,傅里叶红外光谱和介电谱对其表观形貌和电性能进行表征和测试,考察结构与性能之间的关系.     

Soft X-ray Holographic Microscopy with Sub-micrometer Resolution

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Soft X-ray Holographic Microscopy with Sub-micrometer Resolution

Gabor X-ray in-line holograms are recorded with a photoresist at Hefei National Synchrotron Radiation Laboratory. An Atomic Force Microscope (AFM) is used to read the X-ray holograms of minute granules recorded on photoresist PMMA. Digitized hologram is reconstructed by numerical method. The granules with a size less than 0.3 μm can be resolved in the reconstructed image. So the eatimated resolution reaches the level of suibmicrometer.     

Growth mode and effect of carrier gas on In0.53Ga0.47As/InP surface morphology grown with trimethylarsine and arsine

Different growth mode have been observed for InGaAs/InP grown with trimethylarsine and arsine by Metalorganic Vapor Phase Epitaxy (MOVPE) when changing the carrier gas. The surface has been investigated by Atomic Force Microscope (AFM) for epilayers grown at 600°C under pure hydrogen or a mixture of hydrogen and nitrogen as carrier gas. The step/terrace surface morphology was observed for InP/InP and InGaAs/InP (001) using 0.2° off substrates. InP epilayers grown under nitrogen flow show step-bunched terraces as large as 170 nm. The effect of the group V source for InGaAs/InP has been studied. It is shown that the step edge characteristic of step flow growth appears for lattice-matched InGaAs/InP grown with arsine. When using TMAs and hydrogen as a carrier gas, the growth mode and surface roughness depends greatly on V/III ratio and growth temperature. Under nitrogen flow with the combination of TMI+TMG+TMAs, pit-like defects (5–8 nm deep) are visible at high surface concentration (10⁹–10¹⁰/cm²). When increasing V/III ratio, 3D growth occurs simultaneously with pit-like defects, recovering the whole surface of the sample. Various surface morphology characteristics of InGaAs epilayers assessed by AFM characterisation will be presented and discussed.     

Development of a fully automated in-vitro diagnostics system based on low-Q whispering gallery modes in fluorescent microparticles

During the past decade, whispering gallery modes (WGMs) have been proven to enable highly sensitive microscopic optical sensors capable of in-vitro label-free bio-detection under physiological conditions. While the basic aspects of this quite novel and promising approach have been explored, it still lacks implementation at a level that would effectively rival well-established state-of-the-art biosensor systems, such as Surface Plasmon Resonance sensors and Quartz Crystal Microbalance. In this work, we present a fully automated in-vitro diagnostics system based on low-Q whispering gallery modes designed to accept this challenge. Starting from the principles of low-Q WGM sensing, various aspects and intricacies of implementing a fully fletched in-vitro diagnostics system are discussed with special foci on WGM analysis and numerical evaluation, sensor conditioning, fluid handling, and control of the overall device. First results of the performance of the system are presented and interpreted in view of the method’s potential.     

Computer analysis of the AFM images of the nanopore system on the SiO2/Si structure surface,obtained by Zn ion implantation

A computer study of morphological characteristics using AFM images of a self-organized surface nanopore system in the structure of SiO₂/Si(100) is performed. The nanopore system is obtained via Zn ion doping with subsequent thermal annealing. AFM images of the nanopore system are studied using the STIMAN 3D software. A correct quantitative estimate is made of the morphology of this nanopore system using a number of parameters (equivalent diameter, area, total area, and shape coefficient). Estimating the morphology of the self-organized surface nanopore system in the structure of SiO₂/Si(100) allows us to narrow the possible practical applications of the resulting system in opto- and nanoelectronics.     

Parallel and serial generated patterned DLC surfaces for creating three-dimensional polymeric stamp structures

This study demonstrates pattern generation on a highly durable and flat diamond-like-carbon (DLC) film with micro/nano-scale resolution using the Atomic Force Microscope (AFM). Parallel processing (masked lithography) and serial local probe processing (maskless lithography) have both been utilized to produce a range of structure shapes at different length scales. The AFM is operated in the electrical conductivity mode which induces oxidation on the DLC surface. The technique offers features with structure depths as small as 20 nm (serial processing) and pattern replication of many centimeters (parallel processing). Moreover parallel processed structures may be further modified via serial patterning using the same instrumentation. As a result, complex shapes can be produced with a depth being controlled by the DLC film thickness and/or by the bias voltage parameters. The patterned DLC structures can be used as a template for fabrication of 3 dimensional polymeric structures.     

Micromechanism of sulfurizing activated carbon and its ability to adsorb mercury

The effect of ambient environment (dry or wet) and overlapping laser pulses on the laser ablation performance of brass has been investigated. For this purpose, a Q-switched, frequency doubled Nd:YAG laser with a wavelength of 532 nm, pulse energy of 150 mJ, pulse width of 6 ns and repetition rate of 10 Hz is employed. In order to explore the effect of ambient environments, brass targets have been exposed in deionized water, methanol and air. The targets are exposed for 1000, 2000, 3000 and 4000 succeeding pulses in each atmosphere. The surface morphology and chemical composition of ablated targets have been characterized by using Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM) and Attenuated Total Reflection (ATR) techniques. In case of liquid environment, various features like nano- and micro-scale laser-induced periodic surface structures with periodicity 500 nm–1 μm, cavities of size few micrometers with multiple ablative layers and phenomenon of thermal stress cracking are observed. These features are originated by various chemical and thermal phenomena induced by laser heating at the liquid–solid interfaces. The convective bubble motion, explosive boiling, pressure gradients, cluster and colloid formation due to confinement effects of liquids are possible cause for such kind of features. The metal oxides and alcohol formed on irradiated surface are also playing the significant role for the formation of these kinds of structure. In case of air one huge crater is formed along with the redeposition of sputtered material and is ascribed to laser-induced evaporation and oxide formation.     

Investigation of nuclear reaction products by atomic force microscopy

The use of Atomic Force Microscope (AFM, from Corporate Head, Santa Clara, California, USA) opened a new way to study latent nuclear tracks. In our experiments we used plastic track detectors of the type CR-39 (Columbia Resin No. 39) Impinging ions with energy above a threshold of 180 keV can alter the molecular structure forming latent tracks. Since nuclear latent tracks have diameters in the range of 10 to 1000 nm, they can be visualized by AFM with a slight chemical etching (6 min in 6 n NaOH solution at 70 °C). These tracks are significant for the energy, momentum and the mass of the incoming particles. In our study, passive CR-39 detectors were irradiated by secondary particles produced bombarding ¹⁰³Rh by ¹⁶O and ¹²C in a wide range of energy (1 MeV/amu to 33 MeV/amu) at the MP Tandem generator of the Laboratorio Nazionale del Sud in Catania, Italy. The experiment was carried out in order to identify the secondary particles and to determine their density and the spatial distribution.     

Current patterning of 6H-SiC(0 0 0 1) surface by AFM

The Atomic Force Microscope (AFM) with the conducting cantilever has been used as a tool for controlled printing the well-defined shapes of conductive paths on the 6H-SiC(0 0 0 1) surface as well as paths connecting the shapes. For clean 6H-SiC(0 0 0 1) samples the metal-tip/sample contact is of the diode type. The conditions have been found (tip/sample voltage, current) for which the local morphology of the surface is modified during current flow between the tip and the sample. Such a modified surface shows quite a different conduction type of the tip/sample surface contact than that of the unmodified surface.     

消逝场耦合圆柱形微腔中回音壁模式结构的实验研究

采用石英圆柱形微腔与锥形光纤通过消逝场耦合的方式,在实验上观察到了不同半径的柱形微腔中清晰的回音壁模式,耦合效率接近10%. 利用柱形微腔回音壁模式位置和间隔的解析近似公式,对实验所得的透射光谱做了模式的精确标定,共振波长的实验值和标定值间的误差小于0.05nm. 引入回音壁模式的“模场半径”概念,由“模场半径”计算出的模式间隔和实验测量值之间符合很好. 利用透射光谱中的共振波长和理论标定波长间的差值,得到了实验光谱范围内(1295—1320nm)石英光纤的色散曲线,折射率精度达10^-5. 关键词： 圆柱形微腔 回音壁模式 模式标定 模场半径