Interplay between permanent dipole moments and polarizability in positron-molecule binding
Interplay between permanent dipole moments and polarizability in positron-molecule binding
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DOI：
10.1103/physreva.85.022709
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发表时间：
2012-02-17
影响因子：
2.9
通讯作者：
Surko, C. M.
中科院分区：
文献类型：
--
作者：
Danielson, J. R.;Jones, A. C. L.;Surko, C. M.
能量分辨正电子-分子碰撞的研究显示湮灭中的振动Feshbach共振，从而提供了正电子可以与这些物质结合的证据。从振动模式的位置观察到的共振的下移提供了一个测量的正电子分子结合能，其范围从1至300毫电子伏。这里报道的是湮没光谱和结合能的范围更广的化学物种比以前研究，包括醛，酮，甲酸酯，乙酸酯和腈。虽然测得的结合能显示出与分子偶极极化率和永久偶极矩的近似相关性，但对于偶极矩>= 2.0 D，其他效应也很重要。对于这些化合物，它似乎是本地化的正电子波函数附近的一部分的分子导致增强的结合和增加的依赖于分子的偶极矩和电子-正电子的相关性。这些结果的理论计算的关系进行了讨论。
Energy-resolved studies of positron-molecule collisions exhibit vibrational Feshbach resonances in annihilation, thus providing evidence that positrons can bind to these species. The downshifts of the observed resonances from the positions of the vibrational modes provides a measure of the positron-molecule binding energies, which range from 1 to 300 meV. Reported here are annihilation spectra and binding energies for a wider range of chemical species than studied previously, including aldehydes, ketones, formates, acetates, and nitriles. While the measured binding energies show an approximate correlation with molecular dipole polarizability and permanent dipole moment, other effects are important for dipole moments >= 2.0 D. For these compounds, it appears that localization of the positron wave function near a portion of the molecule leads to enhanced binding and an increased dependence on both the molecular dipole moment and the electron-positron correlations. The relationship of these results to theoretical calculations is discussed.