Self-affine surface morphology of plastically deformed metals

We analyze the surface morphology of metals after plastic deformation over a range of scales from 10 nm to 2 mm using atomic force microscopy and scanning white-light interferometry. We demonstrate that an initially smooth surface during deformation develops self-affine roughness over almost 4 orders of magnitude in scale. The Hurst exponent H of one-dimensional surface profiles initially decreases with increasing strain and then stabilizes at H approximately 0.75. We show that the profiles can be mathematically modeled as graphs of a fractional Brownian motion. Our findings can be understood in terms of a fractal distribution of plastic strain within the deformed samples.     

Length scale effect on the deformation microstructures of grown-in twins in copper

Electrodeposited copper samples composed of columnar grains subdivided by alternating twin/matrix (T/M) lamellae have been cold rolled to 30–85% reduction in thickness. The thickness of the T/M lamellae varies over a wide range from a few nanometres to about 1?μm. The deformation microstructure has been characterized systematically. In thin T/M lamellae (below 50–100?nm) the deformation behaviours differ significantly from that of thick T/M lamellae, as the dislocation activity is concentrated at the T/M boundaries illustrated by the observations of stacking faults and Shockley partial dislocations. In thick T/M lamellae (100–1000?nm), the deformation microstructure is related to the grain orientation as also observed previously in deformed single crystals and polycrystals with a grain size at the micrometre scale. The experiment therefore suggests that the universal structural characteristics of deformation microstructure can be extended one order of magnitude from about 5?μm to the sub-micrometre scale (about 0.5?μm).     

Nanoscale deformation measurement by using the hybrid method of gray-level and holographic interferometry

This study extends the use of holographic interferometry to measure the nanoscale out-of-plane displacement with high surface resolution. It is noted that if the deformation is less than half of the optical wavelength, it is hard to find an obvious fringe pattern. Under such a situation, in general, the phase shift method is used. However, it needs to take more than 3 images for phase shifting and phase reconstruction In this paper, a more simple hybrid method of gray-level and holographic interferometry is used to extract fringe skeletons, in which it just needs to take one or two images for the normal deformation measurement directly, even if there exists no obvious fringe pattern. The displacement field with high surface resolution can also be obtained. The proposed method yielded a theoretical precision of 0.15 nm for out-of-plane displacement with a monochromatic CCD camera of 10-bit gray scale (1024 gray scales) sensitivity and microscale surface resolution for millimeter scale object with 640×480 pixels image resolution by an He–Ne LASER (632.8 nm wavelength) light source. The gray-level method is proposed to calculate the non-obvious interferometry fringe by traditional holographic interferometry hologram, and the result showed that this method works for this purpose.     

Homodyne full-field interferometer for measuring dynamic surface phenomena in microstructures

We describe a stabilized homodyne full-field interferometer capable of measuring vertical surface deformations of microstructures in the time domain. The interferometer is stabilized to a chosen operation point by obtaining a feedback signal from a non-moving, freely selectable, reference region on the sample surface. The stabilized full-field interferometer enables detection of time-dependent changes in the surface profile with nanometer scale vertical resolution, while the temporal resolution of the measurement is ultimately limited by the refresh rate of the camera only. The lateral resolution of the surface deformation is determined by the combination of the imaging optics together with the pixel size of the camera. The setup is used to measure the deformation of an Aluminum nitride membrane as a function of time-dependent pressure change. The data analysis allows for unambiguous determination of surface deformations over multiple fringes of the interferogram, hence enabling the study of a wide range of physical phenomena with varying magnitude of vertical surface movement.     

表面热透镜技术测量光学薄膜样品表面热变形

给出了连续调制激励光照射下光学薄膜样品表面热变形场的理论分布,并由此定义了表面热透镜(STL)信号。根据表面热透镜理论实验测量了一个BK7基底高反膜样品的形变,给出了表面热透镜信号随调制频率的变化曲线。实验结果表明:在采用的STL实验构型中,探测了最小1.985 nm的直流形变,对应不调制时的形变为3.97 nm,相应的形变探测灵敏度达到了10 pm量级;直流形变与功率成线性关系;交流表面热透镜信号随着频率增大而减小,在高频端近似成线性减小。     

扫描式超高速摄影中转镜镜面变形量的几何补偿

利用三维有限元计算技术,分析了从三面体到八面体铝合金转镜镜面变形规律.发现以四面体为界,三面体转镜镜面变形为向内凹进,五面体及以上转镜镜面则向外凸出.在对镜面变形定量分析基础上,提出了镜面变形的几何补偿方法,即采用柱面代替平直镜面,使镜面变形后的位置趋近于平直.结果表明,对镜面尺寸17.32 mm,轴向长度32.5 mm的三面体铝合金转镜,在5×104 rpm下,镜面最高点偏离平直镜面的最大值为0.468 μm,是平直镜面的1/9,与相同结构尺寸的铍转镜镜面变形量处于相同量级.说明铝合金转镜采用几何补偿方法,可以在扫描式摄影系统中代替铍转镜.     

表面热透镜技术应用于薄膜微弱吸收测量的理论和实验

由薄膜表面光热形变简化理论和表面热透镜衍射理论导出表面热透镜信号表达式，从理论上证明了表面热透镜信号和薄膜吸收率的线性关系. 应用表面热透镜技术研制了薄膜吸收测量仪，测量结果表明其吸收率测量灵敏度和精度均达10^-6量级. 关键词： 吸收测量 表面热透镜 光热形变 薄膜     

Dynamics at the liquid-vapor interface of a supercooled organic glass former

We investigated the dynamics near the liquid-vapor interface of the supercooled model organic glass former dibutyl phthalate by using surface-sensitive x-ray scattering techniques. Our results reveal significant enhancement of the relaxation rate over a wide length-scales range. The analysis of the dispersion relation of long-wavelength surface fluctuations yields a nonzero value of the share modulus near the free surface. At the molecular level, the dynamics in the near surface region (10-15 nm) is inhomogeneous. The mobility is decreasing with increasing distance from the free surface. Below the bulk glass transition, two distinct relaxation times were observed differing by 1 order of magnitude. The observed fast relaxation proves the existence of a high mobility liquidlike surface layer of 10 nm thickness on top of a frozen in bulk system.     

光刻物镜中透镜高精度支撑结构的设计及分析

光刻投影物镜中透镜的面形精度是影响光学系统成像质量的关键因素之一。为实现透镜面形精度均方根(RMS)值优于2nm的高精度指标,提出一种轴向多点挠性支撑、径向三点可调式定位的光学透镜支撑结构。基于自重变形对支撑结构进行优化设计,深入分析在此支撑结构下自重和热载荷对透镜面形影响。结果表明,重力引起的透镜上表面面形RMS值为0.186nm,下表面面形RMS值为0.15nm。热载荷引起的上表面面形RMS值为0.55nm,下表面面形RMS值为0.54nm。采用这种透镜的支撑结构,能够满足光刻投影物镜中透镜的高精度面形要求。     

经纬仪主镜在支撑系统下的面形变化

为研究在重力作用下主镜支撑系统对经纬仪主镜处于不同工作角度时面形误差的影响,以600 mm口径主镜为研究对象,利用Abaqus软件分别建立了600 mm主镜在加工状态下和工作状态下的有限元支撑模型,并进行了重力变形分析,然后借助4D干涉仪对在不同支撑系统下的主镜进行相关的面形检测。实验结果表明,在吊带支撑系统和主镜室支撑系统下,主镜的自身面形误差RMS为16.18 nm和16.90 nm。利用有限元分析了理想状态的主镜在不同仰角工况下的面形误差,结合主镜自身的面形误差,计算得到了主镜面形误差在光轴由水平变化到竖直的过程中逐渐变大,其RMS最大为19.58 nm,表明该主镜室支撑系统具有良好支撑效果,可满足工程要求,同时也验证了主镜室支撑系统有限元理论模型的准确性。     

In situ observation of dislocation behavior in nanometer grains

Using a newly developed nanoscale deformation device, atomic scale and time-resolved dislocation dynamics have been captured in situ under a transmission electron microscope during the deformation of a Pt ultrathin film with truly nanometer grains (diameter d< ~ 10 nm). We demonstrate that dislocations are highly active even in such tiny grains. For the larger grains (d ~ 10 nm), full dislocations dominate and their evolution sometimes leads to the formation, destruction, and reformation of Lomer locks. In smaller grains, partial dislocations generating stacking faults are prevalent.     

Realization of relative responsivity scale with the electrically calibrated pyroelectric radiometer

In UME, the relative spectral responsivity scale extending from 250 to 2500 nm was realized using electrically calibrated pyroelectric radiometer (ECPR). Its absolute spectral responsivity was determined against the electrical substitution cryogenic radiometer (ESCR) facility at 488.1, 514.6, 532.0, and 632.8 nm with an uncertainty of 1 part in 10⁴ (k=2). The relative spectral responsivity scale of ECPR was derived from the surface reflectance data and absolute spectral responsivity data for the mentioned spectral range. Optical characterization of its spatial non-uniformity (at 632.8 nm) and surface reflectance (over 250–2500 nm wavelength region) indicated that the gold-black absorber is spectrally flat within 0.1%. The total expanded uncertainty in the realization of the mentioned radiometric scale along with ECPR was estimated as 1.74%.     

DUV scattering measurements as a tool for characterization of UV-optical surfaces

A sensitive total-scattering measurement setup for the DUV spectral range is presented, which allows precise determination of both forward and backward scatter losses from optical components for excimer lasers with a sensitivity below 10 ppm for 248 nm and 50 ppm for 193 nm. Scattering from several different coated and uncoated DUV optical surfaces was monitored. For uncoated samples, the backward scatter losses are in good agreement with the predictions of scalar scattering theory, indicating that in this case scattering is mainly determined by surface effects. Although forward and backward scatter losses are of the same order of magnitude for uncoated samples, they differ by up to two orders of magnitude for high-reflection- and by one order of magnitude for anti-reflection-coated samples. The experimental data demonstrate that the anti-reflection coatings suffer from substantial losses due to forward scattering, whereas backward scattering is the predominant loss channel for high-reflection coatings. In addition, the strong influence of defects and impurities on the total scattering is demonstrated. Received: 5 June 2000 / Accepted: 6 June 2000 / Published online: 13 September 2000     

Surface dynamics of polymer films

The dynamics of supported polymer films were studied by probing the surface height fluctuations as a function of lateral length scale using x-ray photon correlation spectroscopy. Measurements were performed on polystyrene (PS) films of thicknesses varying from 84 to 333 nm at temperatures above the PS glass transition temperature. Within a range of wave vectors spanning 10(-3) to 10(-2) nm(-1), good agreement is found between the measured surface dynamics and the theory of overdamped thermal capillary waves on thin films. Quantitatively, the data can be accounted for using the viscosity of bulk PS.     

Elastic friction drive of surface acoustic wave motor

Importance of elastic deformation control to obtain large output force with a surface acoustic wave (SAW) motor is discussed in this paper. By adding pre-load to slider, stator and slider surfaces are deformed in a few tens nanometer. Appropriate deformation in normal direction against normal vibration displacement amplitude of SAW existed. By moderate deformation, the output force of the SAW motor was enlarged up to about 10 N and no-load speed was 0.7 m/s. To produce this performance, the transducer weight and slider size were only 4.2 g and 4 x 4 mm(2).By traveling wave propagation, surface particles of the SAW device move in elliptical motion. Due to the amplitude of the elliptical motion is 10 or 20 nm order, the contact condition of the slider is very critical. To control the contact condition, namely, the elastic deformation of the slider and stator surface in nanometer order, a lot of projections were fabricated on the slider surface. The projection diameter was 20 micro m. In static condition, the elastic deformation and stress were evaluated with the FEM analysis. From this calculation and the simulation result, it is consider that the wave crest is distorted, hence the elasticity has influence on the friction drive condition.Elastic deformation of the stator surface beneath the projection from the initial position were evaluated. In 4 x 4 mm(2) square area, the sliders had from 1089 to 23,409 projections. Depression was independent to the contact pressure. However, the output force depended on the depression although the projection density were different. From the view point of the output power of the motor, the proper depression was independent to the projection density. Around 25 nm depression, the output force and output power were maximized. This depression value was almost same as the vibration displacement amplitude of the stator transducer.     

Depth dependence of photoluminescence and chemical bonding in porous silicon

Porous silicon (PS) is studied by stepwise peeling of the surface layer to clarify the non-uniformity in the photoluminescence (PL) and correlate it with the in-depth chemical bonding and structure of the 30 μm thick layer. The PL intensity grows by an order of magnitude after the peeling off of the first 10 μm and decreases five times in the next 5 μm while the peak maximum position shifts from 730 to 800 nm. X-ray photoelectron spectroscopy (XPS) measurements show that Si–Si and Si–O bonds are present both on the surface and below, and the preferential oxidation state of silicon changes from 3+ and 4+ on the surface to 1+ and 2+ below 10 μm. Using Raman spectroscopy silicon nanocrystals are shown to exist. Their mean size can be estimated at about 3 nm. These results show that the strongest PL comes from a region in the PS layer where silicon nanocrystallites are surrounded by oxides with a low level of oxidation and not from the strongly oxidized surface layer.     

Nano hillock and complex crater formation by low-energy proton implantation with incident angle into lithium niobate single crystal

The formation of nano-size hillocks and simple and complex craters was observed as a result of ion–surface collisions with a lithium niobate single crystal on proton implantation. The low-energy ion implantation process is considered as a controllable and versatile tool for surface and near-surface modifications down to an atomic scale as an alternative to the swift heavy ion irradiation effect. Lithium niobate samples implanted by proton ions with a low energy of 120 keV at various fluences (10¹⁵ and 10¹⁶ protons/cm²) were studied using atomic force microscopy (AFM). The images of surface modification appear as simple and complex crater formation in the case of incident ions at normal to the surface. Varying the angle of incidence to θ=30° with respect to the normal to the surface, hillocks and multi-hillocks were observed. The complex craters with central uplifted, cone-shaped hillocks with a height of up to 4.3 nm are surrounded by low-height (1 nm) rims. The hillock height varies from a few nanometers to 16 nm with the basal diameter from 200 to 340 nm depending on the ion implantation conditions. The complex crater and hillock formation on the lithium niobate sample surface at the collision spot with the impact of incident angle is discussed.     

Investigation of deformation instability of Au/Cu multilayers by indentation

Plastic deformation behavior of Au/Cu multilayers with individual layer thicknesses of 25–250 nm was investigated via microindentation experiments. It was found that plastic instability of the Au/Cu multilayer exhibits strong length scale (individual layer thickness and grain size) dependence. The smaller the length scale, the easier shear bands form. In other words, plastic deformation becomes unstable with decreasing length scale. Cross-sectional observation along with plan-view indicates that the occurrence of plastic deformation instability corresponds to transformation of the deformation mechanism associated with geometrical configuration and length scale of the material. At nanometer scale, buckling-assisted interface crossing of dislocations results in local shear band, while, at submicron scale or above, local dislocation pileup-induced interface offset leads to plastic instability. Theoretical analysis is conducted to understand the length scale-dependent plastic deformation behavior of the multilayer.     

基于简单碰撞理论煤粉燃烧动力学模型的研究-PART Ⅲ:氧气可达比表面积

根据不同温度下氧分子平均自由程的大小,比较了小孔、中孔和大孔中三种扩散速率与煤焦表面燃烧速度的大小.研究表明2000 K以内,颗粒表面分子扩散速率比氧化反应速率大1个数量级以上,过度扩散速率不小于氧化速率.温度小于1200K时,燃烧速率比Knudsen扩散速率小1～5个数量级,扩散孔径小于15～28 nm,反应主要在内外表面进行;1200～1600K时,燃烧速率与Knudsen扩散速率相当,扩散临界孔径28～38 nm,反应在外表面及浅层内表面进行;温度1600K以上时,Knudsen扩散速率比燃烧速率小1个数量级,孔径38～50 nm以下内表面上碳的氧化速度受扩散控制.煤焦的氧化主要发生在Knudsen扩散临界孔径10～50 nm以上的氧气可达表面上.     

光-力耦合受激布里渊散射方程组

 采用位移形式表征各向同性介质的运动，从而对传统的SBS耦合波方程组进行改造，使之适用于多维的情况并体现光学理论和力学理论的耦合。采用有限差分方法数值求解了光学-力学耦合型后向SBS方程组，得到了瞬态的位移场、速度场和应力场。计算结果表明，当泵浦光光强为2.0×10 ¹⁵W/m ²时，SBS可激发厚度为1cm的K9玻璃样品的表面产生出0.1nm量级的位移和10m/s量级的速度，对应的应力幅度达到10MPa量级。