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匿名 發問於 科學及數學其他 - 科學 · 7 年前

relativistic calculation

A beam of 50-keV electrons is directed at a crystal and diffracted electrons are found at an angle of 50* relative to the original beam. What is the spacing of the atomic planes of the crystal?

更新:

天同: why n=1 (first order) ?

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  • 天同
    Lv 7
    7 年前
    最愛解答

    de Brogie wavelength = 6.63x10^-34/square-root[2 x 50x10^3 x 1.6x10^-19 x 9.1x10^-31] m = 5.49x10^-12 m

    Incident angle = 50/2 deg = 25 deg

    Hence, 2d.sin(25) = 5.49 x 10^-12 where d is the atomic plane spacing

    d = 6.5 x 10^-12 m

    2013-10-22 23:13:20 補充:

    Your suppl question.

    It is because n=1 is the FIRST POSSIBLE solution.

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