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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク X-ray crystal truncation rod ： ウィキペディア英語版 X-ray crystal truncation rod X-ray crystal truncation rod scattering is a powerful method in surface science, based on analysis of surface X-ray diffraction (SXRD) patterns from a crystalline surface. For an infinite crystal, the diffracted pattern is concentrated in Dirac delta function like Bragg peaks. Presence of crystalline surfaces results in additional structure along so-called truncation rods (linear regions in momentum space normal to the surface). Crystal Truncation Rod (CTR) measurements allow detailed determination of atomic structure at the surface, especially useful in cases of oxidation, epitaxial growth, and adsorption studies on crystalline surfaces. ==Theory== A particle incident on a crystalline surface with momentum $K\_0$ will undergo scattering through a momentum change of $\backslash mathbf$. If $x$ and $y$ represent directions in the plane of the surface and $z$ is perpendicular to the surface, then the scattered intensity as a function of all possible values of $\backslash mathbf$ is given by $I(\backslash mathbf)=\backslash fracN\_xQ\_xa\_x\; \backslash right\; )\}Q\_xa\_x\backslash right\; )\}\backslash \; \backslash fracN\_yQ\_ya\_y\; \backslash right\; )\}Q\_ya\_y\; \backslash right\; )\}\backslash \; \backslash frac\; \backslash cos\; \backslash left\; (N\_zQ\_zc\; \backslash right\; )\}$ Where $\backslash alpha$ is the penetration coefficient, defined as the ratio of x-ray amplitudes scattered from successive planes of atoms in the crystal, and $a\_x$, $a\_y$, and $c$ are the lattice spacings in the x, y, and z directions, respectively. 〔E. Conrad (1996). "Diffraction Methods". In W. N. Unertl (Ed.), ''Physical Structure'', pp. 279-302. Amsterdam: Elsevier Science.〕 In the case of perfect adsorption, $\backslash alpha\; =\; 0$, and the intensity becomes independent of $Q\_z$, with a maximum for any $\backslash mathbf$ parallel to the crystal surface) that satisfies the 2D Laue condition in reciprocal space $\backslash mathbf\_\backslash parallel\; =\; \backslash mathbf\_\; =\; h\backslash mathbf^$ *_x + k\mathbf^ *_y for integers $h$ and $k$. This condition results in rods of intensity in reciprocal space, oriented perpendicular to the surface and passing through the reciprocal lattice points of the surface, as in Fig. 1. These rods are known as diffraction rods, or crystal truncation rods. When $\backslash alpha$ is allowed to vary from 0, the intensity along the rods varies according to Fig. 2. Note that in the limit as $\backslash alpha$ approaches unity, the x-rays are fully penetrating, and the scattered intensity approaches a periodic delta function, as in bulk diffraction. This calculation has been done according to the kinematic (single-scattering) approximation. This has been shown to be accurate to within a factor of $10^$ of the peak intensity. Adding dynamical (multiple-scattering) considerations to the model can result in even more accurate predictions of CTR intensity. 〔V. M. Kaganer (2007). Crystal truncation rods in kinematical and dynamical x-ray diffraction theories. ''Phys. Rev. B'' 75 245425.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「X-ray crystal truncation rod」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.