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1、实验名称:X射线实验一、实验目的:1 .了解X射线的产生及有关晶体的基本知识。2 .掌握晶体中X射线衍射理论。3 .测量单晶NaC1、1iF的晶面距及晶格常数。二、实验仪器:55481型X射线衍射仪:Nac1单晶,面心立方体结构,表明:平行(IOO)三、实验原理:1 .布拉格方程设一束波长为的单色X射线射到晶体上,入射X射线将被晶体中原子的电子散射,每一个原子构成散射波的波源,这些散射波是相干的,在某个方向上的衍射波就是从晶体中全部原子所发出的波在这个方向上的叠加。只有当散射波之间的光程差等于零或波长的整数倍时,才在空间互相加强,否则将相互抵消。研究X射线在晶体中衍射时,可把晶体看作是由某一晶
2、面族所组成,X射线平行地入射到晶面族上,如图1所示。先就一个晶面A看,根据惠更斯原理,衍射线就是原射线在该晶面上的反射线。由于X射线的透射能力强,在研究它在晶面族中衍射时,不仅要考虑第一个晶面A的反射,而且要考虑来自相继的晶面B,V的反射,这些来自相继晶面的反射线之间有一定的光程差,因而发生干涉。对晶面距为d的两个相邻晶面来说其反射线之间的光程差为2dsin(0为掠射角)。只有当2dsin=nn=1,2,3.(1)得到满足时,各个晶面的反射线才互相加强,从而产生衍射线。(1)式称为布拉格方程,它表明,当产生一定波长入的X射线在晶面距为d的晶面族上,则只有某种X射线其波长满足(1)式才能产生衍射
3、线。至于衍射线的方向,无论上诉哪种情况,都是原射线在晶面上反射的方向。通常说晶面反射X射线,应该按上诉含义来理解,这种反射称为选择反射。2 .晶体中X射线衍射的光路图本实验所使用的554-81型组合式衍射仪主要由以下几部分组成:X射线定位测角器、传感器、Geige1MUI1er计算机等。X射线管发出谱线,经错滤波片下Ka线(入Ka=0.711A)在经准直器变平行的单色X射线。晶体的角位置(0)测角器测量,通过传感器使计数管和(靶)以2:1的角耦合旋转,X射线晶体,反射光射向Geiger-Mu11er计由此记录反射光子弹数率N(单位为将数据传输给计算机,就可得到晶体的0-N关系)四、实验内容1将
4、待测晶体放置在靶台上。3 .打开主电源开关(左侧面)4 .按U键,用ADJUST旋钮进行设置:U=35KV按I键,用ADJUST旋钮进行设置:1=1.OOmA5 .按At,AB键,用ADJUST旋钮设置所需值。按CoUP1ED键81IM1TS键,用ADWST旋钮设置所需值(8二30度)。6 .启动软件uX-rayApparatus,o7 .按CoUP1ED键及SCANON/OFF键,开始扫描。8 .按ZERO键,使靶和传感器臂回到零位置。9 .获取实验数据10 关闭主电源开关,打开铅玻璃滑门,将样品放回到原处。五、数据处理与结果0.06864.27818.430012.63090.14604.
5、37728.531812.72640.22564.48118.629312.81440.31104.58058.727412.91080.41024.68038.825613.01160.53234.78148.926013.11080.612574.88379.026913.21080.739954.97899.121213.3830.828805.07629.219413.41180.912925.17859.318013.5871.08955.27609.418213.61051.16505.37279.519613.7841.25255.46799.617413.8931.33535.
6、57019.717413.91171.42295.66789.815814.01461.5885.76839.916614.14241.6525.870110.012114.27501.7135.999310.116414.36891.8146.0139610.214514.43821.9126.1141610.315014.51502.086.2114810.414614.61092.1136.373310.513014.7792.2156.460810.613814.8782.3166.559910.713314.9692.4116.665810.813615.0882.5106.7106
7、710.912715.1772.6166.8229311.013115.2722.7186.9311211.113315.3722.8207.0262811.211915.4672.9147.1127911.311915.5793.0197.266611.412015.6543.1517.349011.510115.7723.21427.443211.612015.8623.32507.543211.78515.9753.43837.638311.811716.0653.54347.740011.911716.1703.65617.839612.010416.2733.76267.937212
8、.112016.3703.86398.037312.211516.4503.97218.134712.313816.5764.07728.229812.415216.6624.17608.328912.522516.75316.85821.12825.42529.72316.95321.22925.52129.84317.05221.32925.61829.94917.16321.42225.71830.03117.25421.53325.82417.36121.64325.93117.46221.711126.01817.54221.816226.13317.65421.915626.216
9、17.73822.011226.32317.84322.15426.43417.95122.23026.52618.04322.33326.61318.14222.43026.71818.23622.52826.81118.34922.62526.91218.44422.73127.01318.54522.83327.11618.63522.92327.21018.73323.03027.32818.83923.12027.41918.94823.22427.52119.04123.32127.61719.15223.41327.71319.27323.51727.81719.39323.63
10、027.91519.46223.71928.01019.54023.82428.12019.63423.92328.21719.73724.01828.31319.83424.11928.41319.93524.21928.51620.02924.32228.61520.13424.41928.71620.24324.52328.81220.34024.62228.92020.42724.71629.01820.52624.81329.11420.63424.91529.22220.74425.02029.31320.83825.12529.42020.93125.22129.52021.02725.31929.615六、结果讨论与思考根据公式:2dsin=n=0.711AX射线照射到