近日,美国加利福尼亚大学圣地亚哥分校的C. M. Surko及其研究小组与英国贝尔法斯特女王大学的D. G. Green等人合作并取得一项新进展。经过不懈努力,他们揭示了芳香分子和其他环状分子中的正电子湮灭和结合过程。相关研究成果已于2024年6月4日在国际知名学术期刊《物理评论A》上发表。
本文解析了芳香族分子和杂环分子的湮灭光谱,通过基于势阱的正电子束作为入射正电子能量的函数进行研究。通过与振动模式光谱的对比,他们得出了正电子-分子的结合能。利用从头计算的多体理论进行预测,充分考虑了电子-正电子之间的相关关系,包括虚拟正电子的形成,结果显示与实验测量的结合能高度吻合。
计算进一步揭示了永久偶极矩和键之间的竞争,如何影响束缚态正电子密度的空间分布。此外,本文还深入探讨了这些结果的意义,以及多模特征在这些分子湮灭过程中所起的作用,特别关注了费米共振的影响。
附:英文原文
Title: Positron annihilation and binding in aromatic and other ring molecules
Author: E. Arthur-Baidoo, J. R. Danielson, C. M. Surko, J. P. Cassidy, S. K. Gregg, J. Hofierka, B. Cunningham, C. H. Patterson, D. G. Green
Issue&Volume: 2024/06/04
Abstract: Measured annihilation spectra are presented for aromatic and heterocyclic ring molecules resolved as a function of incident positron energy using a trap-based positron beam. Comparisons with the vibrational mode spectra yield positron-molecule binding energies. Ab initio many-body theory predictions, which take proper account of electron-positron correlations including virtual-positronium formation, are presented and are found to be in good to excellent agreement with the measured binding energies. The calculations elucidate the competition between permanent dipole moments and bonds in determining the spatial distribution of the bound-state positron density. The implications of these results and the role of multimode features in annihilation in these molecules, including Fermi resonances, are discussed.
DOI: 10.1103/PhysRevA.109.062801
Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.062801
Physical Review A:《物理评论A》,创刊于1970年。隶属于美国物理学会,最新IF:2.97
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