• Bulletin of the Korean Chemical Society
• /
• v.32 no.2
• /
• pp.389-398
• /
• 2011

Although the currently available surface spectroscopic techniques provide powerful means of studying atoms and simple molecules on surfaces, the identification of complex molecules and functional groups is a major concern in surface analysis. This article describes a recently developed method of surface molecular analysis based on reactive ion scattering (RIS) of low energy (< 100 eV) $Cs^+$ beams. The RIS method can detect surface molecules via a mechanism in which a $Cs^+$ projectile picks up an adsorbate from the surface during the scattering process. The basic principles of the method are reviewed and its applications are discussed by showing several examples from studies of molecules and their reactions on surfaces.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.11
• /
• pp.76-83
• /
• 2007

The dark-field laser scattering system has been developed to inspect surface defects in infrared cut-off filters and then laser scattering characteristics against the defects are investigated. The qualitative analysis for the reliable and accurate detection performance is described through the correlation between incident angles of a laser and viewing ones of a camera. In this paper, reliable and important information with laser scattering is given for the surface defect inspection of IR filters. Its performance has been verified through various experiments.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.2 no.2
• /
• pp.157-165
• /
• 1999

Production and measurement of a super-polished few-ppm-scattering mirror substrate are investigated. In order to improve the surface roughness directly determining scattering, the super-polishing process using Bowl-Feed technique is tried. The surface quality of the super-polished substrate is estimated by the phase-measuring interferometer. For the reliable roughness measurement using the interferometer, data averaging method is applied so that the optimal data averaging condition, 30 phase-data averaging and 20 intensity-data averaging, minimizing the measurement error is experimently searched. Based on the optimal data averaging condition, surface roughness of home-made mirror substrate is measured to be less than $0.5{\AA}$ rms corresponding to 2-ppm total-integrated-scattering.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.2
• /
• pp.267-280
• /
• 1992

This paper describes a numerical analysis of the light scattering patterns of roughness profiles. This analysis was based upon the light scattering theory developed by Beckmann. In the analysis, the roughness profile was regarded as a profile whose irregularities depend on the production process and the shape of cutting tool. Generally, waviness of an actual surface seriously distorts the scattered pattern of roughness profile. In order to avoid the effects of waviness of actual surfaces, several theoretically calculated scattering patterns, instead of actual scattering patterns, were used to analyze the scattering patterns of typical engineering roughness profiles. The characteristics of the light scattering patterns for five model surfaces were studied.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.1
• /
• pp.107-114
• /
• 2011

In this study, a correlation between the roughness of nanoscale lapping surface and its laser scattering pattern has been identified experimentally. The characteristics of laser scattering on a reflected surface are investigated, and a laser scattering mechanism is newly designed by adopting the dark-field method. Laser scattering patterns resulting from nanoscale lapping shape are in the shape of crossed irregular lattice. In addition, optimum laser scattering images are obtained by the design of experiment, and the roughness of nanoscale lapping surface is estimated using regression analysis certain useful features of the laser scattering patterns. The results of fifty experiments on three types of nanoscale lapping surfaces show that the roughness of nanoscale lapping surfaces can be accurately estimated by the proposed mathematical modeling method.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.1
• /
• pp.35-41
• /
• 2010

In this paper, surface roughness has been experimentally identified using laser scattering images. The parameters and optical deflected rays of laser scattering are investigated on laser scattering system, and then their optimum parameters on grinding surfaces are selected using design of experiment. The application of the optimum parameters results in featured laser scattering images, in which the mean of vertical scattering distributions is regarded as a feature. It is shown that the feature of laser scattering distributions is linearly increased according to grinding surface roughness and so the information can be used as important factor for the measurement and evaluation of various surface roughness. In the future, the performance of the proposed laser scattering method will be evaluated using AFM.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11a
• /
• pp.252-256
• /
• 2001

Scattering of surface materials has been known as one of the most important aspects in evaluating the acoustics of concert halls are designed. One of the methods that can reduce the errors in estimating the reverberation time and other acoustic parameters through computer modeling is to calculate scattering coefficient of surface materials. However. so far, no objective and reliable methods measuring scattering coefficient has been suggested. In this situation, ISO has suggested the method of measuring the random-incidence scattering coefficient on surfaces in diffuse field, whereas AES has introduced a method on directional-incidence in free field. In this study, the scattering coefficients of five kinds of hemispheres (1.5, 2.0. 2.5. 3.0. 3.5cm) were measured by using the ISO method in 1：10 reverberation chamber. It was found that 3.0cm hemisphere has the highest scattering coefficient satisfying 95％ reliability.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2013.05a
• /
• pp.97-97
• /
• 2013

We present a comprehensive study on the integration of h-BN with silicon MOSFET. Temperature dependent mobility modeling is used to discern the effects of top-gate dielectric on carrier transport and identify limiting factors of the system. The result indicates that coulomb scattering and surface roughness scattering are the dominant scattering mechanisms for silicon MOSFETs at relatively low temperature. Interposing a layer of h-BN between $SiO_2$ and Si effectively weakens coulomb scattering by separating carriers in the silicon inversion layer from the charged centers as 2-dimensional h-BN is relatively inert and is expected to be free of dangling bonds or surface charge traps owing to the strong, in-plane, ionic bonding of the planar hexagonal lattice structure, thus leading to a significant improvement in mobility relative to undecorated system. Furthermore, the atomically planar surface of h-BN also suppresses surface roughness scattering in this Si MOSFET system, resulting in a monotonously increasing mobility curve along with gate voltage, which is different from the traditional one with a extremum in a certain voltage. Alternatively, high-k dielectrics can lead to enhanced transport properties through dielectric screening. Modeling indicates that we can achieve even higher mobility by using h-BN decorated $HfO_2$ as gate dielectric in silicon MOSFETs instead of h-BN decorated $SiO_2$.

• Proceedings of the KSRS Conference
• /
• 2008.10a
• /
• pp.33-36
• /
• 2008

This paper presents soil moisture retrieval from measured polarimetric backscattering coefficients of a vegetated surface. Based on the analysis of the quite complicate first-order radiative transfer scattering model for vegetated surfaces, a simplified scattering model is proposed for an inversion algorithm. Extraction of the surface-scatter component from the total scattering of a vegetation canopy is addressed using the simplified model, and also using the three-component decomposition technique. The backscattering coefficients are measured with a polarimetric L-band scatterometer during two months. At the same time, the biomasses, leaf moisture contents, and soil moisture contents are also measured. Then the measurement data are used to estimate the model parameters for vv-, hh-, and vh-polarizations. The scattering model for tall-grass-covered surfaces is inverted to retrieve the soil moisture content from the measurements using a genetic algorithm. The retrieved soil moisture contents agree quite well with the in-situ measured soil moisture data.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.725-728
• /
• 2005

The scattering problem of the randomly rough surface is examined by the method of moments(MoM), small perturbation method (SPM), integral equation method (IEM) and the semi-empirical polarimetic model. To apply the numerical technique of the MoM to microwave scattering from a rough surface, at first, many independent randomly rough surfaces with a rms height and a correlation length are generated with Gaussian random deviate. Then, an efficient Monte Carlo simulation technique is applied to estimate the scattering coefficients of the surfaces.