Experimental and Theoretical Studies of Electron-Impact Excitation of Neon
Experimental and Theoretical Studies of Electron-Impact Excitation of Neon
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氖电子碰撞激发的实验与理论研究
DOI：
10.1103/physreva.2.1305
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发表时间：
1970
影响因子：
2.9
通讯作者：
F. E. Fajen
中科院分区：
文献类型：
--
作者：
F. A. Sharpton;R. John;C. Lin;F. E. Fajen
用光学方法测量了2p5ns、2p5np和2p5nd构型中约50个态的电子激发函数。来自上层的级联修正只对np状态很重要，通常占总人口的50%。如果用LS本征函数来表示氖激发态的波函数，那么用态的量子数L和S来表征氦的激发行为的方案可以延续到氖。例如，所有的光学允许态都表现出非常宽的激发函数和大的截面，而纯三重态具有狭窄的激发函数。对于其他态，波函数可表示为三重态和偶极禁止单重态的线性组合；因此，激励函数具有中间宽度。从群论的论证中，我们证明了在构型2p5nl内，J+ l为奇值的态比偶值的态具有更大的激发截面。我们的实验数据很好地证实了这一理论规律。此外，我们从理论上推导出np态的Q (J= 0)> Q (J= 2)， nd态的Q (J= 1)> Q (J= 3)；在更严格的情况下，对于np Q (J= 1)> Q （J= 3）对于nd Q (J= 2)> Q （J= 0,4）。这些关系与实验结果基本一致，只有少数例外。实验数据的大多数定性和半定量特征可以通过氦的结果的推广和简单的理论考虑来理解。利用Hartree-Fock-Slater轨道构造的原子波函数，用Born近似计算了J+ l为奇值态的激发截面，并对中间矢量耦合进行了半经验处理。理论值与实验值的吻合大体上是令人满意的。偶（J+ l）态受到间接耦合的强烈影响；因此，没有尝试将这些状态的实验数据与玻恩近似计算进行比较。
The electron excitation functions of some fifty states from the 2 p 5 ns, 2 p 5 np, and 2 p 5 nd configurations have been measured by the optical method. Corrections due to cascade from the upper levels are important only for the np states and typically amount to 50% of the total population. The scheme of characterizing the excitation behaviors of helium by the quantum numbers L and S of the states can be carried over to neon if one expresses the wave functions of the excited states of neon in terms of the LS eigenfunctions. For example, all the optically allowed states exhibit very broad excitation functions and large cross sections, and the purely triplet states have narrow excitation functions. For the other states, the wave functions are expressible as linear combinations of those of triplet states and dipole-forbidden singlet states; hence, the excitation functions have intermediate widths. From group-theoretical arguments, we have shown that within a configuration 2 p 5 nl, the states with odd values of J+ l have larger excitation cross sections than the ones with even values. This theoretical rule has been well confirmed by our experimental data. In addition, we have deduced theoretically that Q (J= 0)> Q (J= 2) for the np states, and Q (J= 1)> Q (J= 3) for nd; and in a more restricted way, that Q (J= 1)> Q (J= 3) for np and Q (J= 2)> Q (J= 0, 4) for nd. These relations are in good agreement with experiment with only a few exceptions. Most of the qualitative and semiquantitative features of the experimental data can be understood from generalization of the results of helium and by simple theoretical considerations. The excitation cross sections of the states with odd values of J+ l have been calculated by the Born approximation using atomic wave functions constructed by the Hartree-Fock-Slater orbitals, together with a semiempirical treatment of the intermediate vector coupling. The agreement between the theoretical and experimental values is generally satisfactory. The even-(J+ l) states are strongly influenced by indirect coupling; thus, no attempt was made to compare the experimental data of these states with the Born-approximation calculations.