弗兰克赫兹实验_论文讲解

1、弗兰克赫兹实验 第一激发电势的测定论文学校: 学院: 专业： 组员： 指导教师： 职称：副教授 2012年7月 1日星期一摘要：本实验通过改变灯丝电压， 得观察和理解分析， 得到氩原子的第一激发电势 。关键词：弗兰克 赫兹 汞第一激发态 近代物理实验（一） 引言 1913 年丹麦物理学家玻尔（NBohr）提出并建立了玻尔原子模型理论，认 为有原子能级存在。光谱学的研究证明了原子能级的存在，原子光谱中的每根谱线都相应表示了原子从某一较高能态向另一较低能态跃迁时的辐射。然而，原子能级的存在除了可由光谱研究推得外，1914 年德国物理学家夫兰克和赫兹用慢电子与稀薄气体原子碰撞的方法，使原子从低能级激

2、发到高能级。通过测量电子和原子碰撞时交换某一定值的能量，观察测量到了汞的激发电位和电离电位，直接证明了原子内部量子化能级的存在，也证明了原子发生跃迁时吸收和发射能量是完全正确的、不连续的，为早一年玻尔发表的原子结构理论的假说提供了有力的实验证据。他们因此而分享了1925 年诺贝尔物理学奖。其实验方法至今仍是探索原子结构的重要手段之一。玻尔因其原子模型理论获 1922 年诺贝尔物理学奖，而夫兰克与赫兹的实验也于 1925年获此大奖。夫兰克-赫兹实验与玻尔原子理论在物理学的发展史中起到了重要的作用。 （二） 实验设备 （ 电脑XDFP软件 F-H实验管 WNZK-维度控制仪 FH-II弗兰克赫兹试

3、验仪 ）（三） 实验原理夫兰克-赫兹实验的物理过程图1 夫兰克-赫兹实验原理图 图中左侧为夫兰克-赫兹管（F-H管），它是一种密封的玻璃管，其中充有稀薄的原子量较大的汞或惰性气体原子。在这里灯丝用来对阴极K加热，使其发射热 电子。灯丝电压Ur越高，阴极K发射的电子流也就越大。第一栅极G1的主要作用是消除空间电荷对阴极电子发射的影响。栅极G1和阴极K之间的电压通常只有几伏。第二栅极G2的作用是在G2和K之间形成对电子加速的静电场。由阴极K发射的绝大多数热电子被栅极G1和G2所接收，并且其中被栅极G2接收的比例随加速电压UG2K的升高而增大。少量的发射电子穿过栅极G2达到极板P，形成板流IP。板流

4、IP的大小由微电流测试仪进行测量。在板极P和G2之间加有一反向拒斥电压UG2P，它对电子减速，使经过碰撞后动能非常低的电子折回并被栅极G2接受，从而起到调节板流IP大小的作用。 设汞原子的基态能量为E1，第一激发态能量为E2，且由热阴极发射的电子初速度为零。受加速电场U2作用，电子到达栅极G2时所获得的能量为E=eU2 ，具有这种能量的电子与汞原子发生碰撞。当U2较低时，电子能量eU2小于原子的激发能（即eU2eUG2P时，电子又能到达板极，使板流IP回升。当U2增大到2U0时，电子经第一次非弹性碰撞后的剩余能量足以使其与汞原子产生第二次非弹性碰撞，汞原子再次从电子中取得能量，能量交换的结果使

5、IP再次下降。同理可知，U2继续增大时，电子会在第二栅极G2附近与汞原子发生第三次、第四次、非弹性碰撞，引起板流IP的相应下跌。可见，随着加速电压U2的增加，板流IP会周期性地出现极大值和极小值，凡满足加速电压U2=nU0（n=1,2,3,）时，板流IP都会相应下跌，形成规则起伏的IP-U2特性曲线。曲线各峰值之间的等间隔规律表明：碰撞过程中电子有确定的能量传递给汞原子，而与相邻的两板流极大值（或极小值）所对应的加速电压的差值就是汞原子的第一激发电位U0 。它的公认值为4.9V。 图2 充汞F-H管的Ip-U2特性曲线 （四） 实验数据处理 （一） 氩原子第一激发电势的测定。 表一 实验参数记

6、录电流量程10uAVg1k1.1v灯丝电压2.8vVg2k4.5v起始电压0v测量步距0.1终止电压100v温度27.0等待时间0.4s 表二 氩原子第一激发电势峰值峰谷数值记录表峰值电压 (/v)14.225.136.448.460.773.586.8峰谷电压 (/v)19.030.442.154.366.879.8 根据公式： Vgk=nvg (n=1.2.3.4) 令Y=k*x+b (其中k=vg n=x)所以根据最小二乘法 利用EXCEL可以求得 根据表二中的数据（一） 利用其峰值计算第一激发电势 k=12.105v r*r=0.997997 SA(x)=0.22v 所以： Vg=12

7、.11v r=0.998998 SA(Vg)=0.22v 所以： Vg=(12.11+-0.22) v根据表二中的数据（二） 利用其谷值计算第一激发电势 k=12.161v r*r=0.999897 SA(x)=0.18v 所以： Vg=12.161v r=0.99995 SA(Vg)=0.18v 所以： Vg=(12.16+-0.18) v （三） 氩原子 IpVg2k的测定 表3. IpVg2k数据记录表 004.4108.81213.2200.104.5108.91413.3210.204.61091313.4200.304.7109.11313.5200.404.8109.21213.

8、6210.504.9109.31313.7210.605109.41213.8200.705.1109.51313.9220.805.2109.612140.905.3109.71214.123105.4109.81414.2231.105.5109.91414.3221.205.610101314.4231.3105.71010.11214.5231.4105.81210.21314.6241.5105.91210.31314.7251.61061310.41214.8251.7106.11210.51314.9241.8106.21110.61315251.9106.31210.71315

9、.1262106.41210.81515.2262.1106.51210.91415.3252.2106.613111415.4262.3106.71111.11415.5272.4106.81211.21415.6262.5106.91211.31315.7262.61071.211.41415.8262.7107.11011.51415.9262.8107.21211.61516262.9107.31111.71416.1263107.41211.81516.2253.1107.51211.91516.3253.2107.6121716.4253.3107.71112.11516.5253

10、.4107.81212.21516.6253.5107.91212.31716.7243.61081112.41716.8253.7108.11312.51716.9243.8108.21112.61717233.9108.31212.71717.1234108.41212.81817.2224.1108.51312.91917.3224.2108.613131917.4224.3108.71313.11917.52217.621225726.46226.46217.72122.15826.56326.56317.82022.25626.66326.66317.92122.35326.7612

11、6.761182122.45226.76026.76018.12222.55326.95926.95918.22122.6552758275818.32222.75427.15827.15818.42222.85527.25727.25718.52322.95527.35527.35518.624235627.45327.45318.72423.15827.55227.55218.82623.25527.65027.65018.92623.35627.74727.747192723.45827.84727.84719.12823.55827.94427.94419.22923.65828422

12、84219.33023.75828.14128.14119.43123.85928.23928.23919.53323.96628.33628.33619.635246028.43628.43619.73724.15928.53328.53319.83824.26028.63328.63319.93924.36128.72928.729204224.46128.82428.82420.14324.55928.92428.92420.24424.6612922292220.34624.76129.12029.12020.44624.86129.21929.21920.54924.96129.31

13、829.31820.650256229.41829.41820.75125.16329.51729.51720.85225.26329.61729.61720.95425.36329.71729.717215525.46329.81629.81621.15525.56329.91829.91821.25525.6643018301821.35825.76330.12030.12021.45925.86330.22330.22321.56025.96430.32430.32421.661266330.42530.42521.75626.16330.52830.52821.85626.26230.

14、63030.63021.95526.36330.73230.73226.46235.210135.210135.210126.56335.310135.310135.310126.66335.410135.410135.410126.76135.510335.510335.510326.76035.610335.610335.610326.95935.710235.710235.7102275835.810235.810235.810227.15835.910235.910235.910227.25736103361033610327.35536.110436.110436.110427.45

15、336.210336.210336.210327.55236.310436.310436.310427.65036.410336.410336.410327.74736.510336.510336.510327.84736.610236.610236.610227.94436.710336.710336.7103284236.810336.810336.810328.14136.910236.910236.910228.23937102371023710228.33637.110137.110137.110128.43637.210037.210037.210028.53337.310037.

16、310037.310028.63337.410037.410037.410028.72937.59937.59937.59928.82437.69937.69937.69928.92437.79737.79737.797292237.89737.89737.89729.12037.99637.99637.99629.21938963896389629.31838.19438.19438.19429.41838.29138.29138.29129.51738.39238.39238.39229.61738.49038.49038.49029.71738.58838.58838.58829.816

17、38.68638.68638.68629.91838.78338.78338.783301838.88338.88338.88330.12038.97938.97938.97930.22339773977397730.32439.17439.17439.17430.42539.27039.27039.27030.52839.36939.36939.36930.63039.46639.46639.46630.73239.56439.56439.56448.412748.412748.412748.412748.512648.512648.512648.512648.612648.612648.6

18、12648.612648.712648.712648.712648.712648.812448.812448.812448.812448.912548.912548.912548.91254912549125491254912549.112249.112249.112249.112249.212249.212249.212249.212249.312249.312249.312249.312249.412149.412149.412149.412149.512049.512049.512049.512049.611849.611849.611849.611849.711849.711849.7

19、11849.711849.811649.811649.811649.811649.911449.911449.911449.91145011350113501135011350.111250.111250.111250.111250.211050.211050.211050.211050.310850.310850.310850.310850.410750.410750.410750.410750.510650.510650.510650.510650.610250.610250.610250.610250.710050.710050.710050.710050.89850.89850.898

20、50.89850.99750.99750.99750.997519551955195519551.19051.19051.19051.19051.28851.28851.28851.28851.38651.38651.38651.38651.48551.48551.48551.48551.58351.58351.58351.58351.67951.67951.67951.67951.77751.77751.77751.77751.87651.87651.87651.87651.97451.97451.97451.974527152715271527152.16952.16952.16952.1

21、6952.26852.26852.26852.26852.36752.36752.36752.36752.46552.46552.46552.46552.56452.56452.56452.56452.66452.66452.66452.66452.76252.76252.76252.76257.211761.6138669170.413757.312061.713766.19070.514057.412261.813766.29070.614157.512161.913666.39170.714157.61256213566.49270.814257.712562.113366.59370.

22、914557.812662.213266.6937114457.912862.313266.79471.11455812962.413066.89471.214658.113262.512866.99571.314858.213262.6129679671.414758.313462.712967.19671.514958.413362.812767.29671.615058.513562.912667.39871.715058.61366312467.49971.815258.713663.111767.59971.915258.813763.211467.61017215258.91396

23、3.311167.710372.11555913963.410967.810372.215459.114063.510867.910372.315459.213863.61076810572.415559.314163.710468.110872.515659.414263.810468.210972.615659.514263.910368.311072.715559.61436410168.411172.815559.714364.19968.511372.915759.814364.29968.61147315759.914464.39868.711673.11566014364.497

24、68.811773.215660.114564.59568.911973.315760.214564.6956912073.415660.314464.79469.112173.515560.414464.89369.212273.615660.514464.99269.312573.715560.6144659269.412573.815560.714465.19169.512673.915660.814365.29169.61297415360.914365.39069.712974.11536114365.49169.813274.215261.114265.59069.913274.3

25、15261.214165.6907013474.415161.314065.78970.113574.515061.414165.89170.213474.615161.513965.99170.313774.714874.814779.212683.61628817374.914779.312683.716388.11747514679.412683.816588.217275.114779.512783.916588.317275.214579.61268416688.417175.314479.712784.116788.517175.414479.812884.216888.61717

26、5.514279.912884.316988.717075.61418013084.417088.816975.714180.113084.517188.917175.813980.213084.61728917075.913980.313184.717189.11697613880.413284.817289.216776.113880.513384.917189.316976.213680.61338517389.416976.313680.713585.117389.516776.413580.813585.217389.616876.513480.913785.317489.71677

27、6.61328113785.417589.816776.713281.113685.517589.916776.813181.213885.61759016576.913181.313985.717590.11667712981.414085.817590.216577.112881.514185.917690.316577.212881.61418617790.416577.312881.714286.117590.516477.412781.814486.217590.616577.512781.914586.317790.716577.61268214686.417790.816477.

28、712682.114786.517590.916477.812582.214986.61769116377.912682.314986.717591.11647812582.415086.817791.216278.112582.515286.917791.316278.212582.61538717691.416478.312582.715487.117491.516378.412582.815487.217491.616378.512582.915587.317591.716278.61248315787.417591.816478.712583.115787.517391.916478.812583.215887.