Double Photoionization of Molecules by One or More Photons: A Sensitive Probe of Electronic Correlation

一个或多个光子对分子的双光电离：一种灵敏的电子相关探针

• 批准号: 0604628
• 负责人: C. William McCurdy
• 金额: --
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0604628&HistoricalAwards=false
• 关键词: Double; Photoionization; Molecules; More; Photons

This project will explore the physics of the double photoionization of molecules by one photon and by the non-sequential absorption of two photons. These processes add molecular many-electron correlation to the already challenging three-body Coulomb breakup problem, by placing two electrons in the continuum of a molecular ion. In recent years the atomic versions of these problems have begun to yield to new theoretical methods. The even richer physics of molecular double photoionization is now becoming accessible experimentally.A new class of momentum imaging experiments has matured over roughly the past decade.Those experiments detect the momenta of all the charged particles emerging from the double photoionization event in coincidence and reconstruct the alignment, and even the internuclear distance, of the molecule at the time of photoabsorption. Therefore the powerful new experimental ingredients for a novel kind of spectroscopy are in place, but there is insufficient theory available to understand it. The research develops the methods that will open the way to an accurate description of double photoionization of diatomic molecules, treating the many-electron aspects of the problem as well as the dynamics of the outgoing electrons in ab initio numerical calculations. The basic theoretical approach makes use of the method of exterior complex scaling (ECS), which has been successful in treating two electron systems. A hybrid basis method is proposed that combines the grid methods that have been used for ECS calculations in the past with the Gaussian basis methods of quantum chemistry used to describe the target. This technology simultaneously addresses the problems of treating two continuum electrons and the correlation of the initially and finally bound electrons of the molecular target.Non-sequential two-photon double ionization of atoms and molecules in intense fields will be treated with the same methods. A novel approach to that problem is proposed that can completely describe two photon double ionization of helium and H2. Together with these theoretical predictions, new experiments that can be performed with existing instrumentation will be able to answer many open questions about this fundamental intense field process.

这个项目将探索分子的双光致电离的物理由一个光子和两个光子的非顺序吸收。这些过程通过将两个电子放置在分子离子的连续体中，将分子多电子相关性添加到已经具有挑战性的三体库仑破裂问题中。近年来，这些问题的原子版本已经开始屈服于新的理论方法。在过去的十年中，一种新的动量成像实验已经发展成熟，这些实验可以探测到从双光电离事件中出现的所有带电粒子的动量，并重建分子在光吸收时的排列，甚至是核间距离。因此，一种新的光谱学的强大的新的实验成分已经到位，但没有足够的理论来理解它。这项研究开发的方法，将开辟一条道路，以准确描述双原子分子的双光电离，处理多电子方面的问题，以及在从头算数值计算中的出射电子的动力学。基本的理论方法是利用外复标度（ECS）的方法，这已成功地处理两个电子系统。提出了一种混合基方法，它结合了过去用于ECS计算的网格方法和用于描述目标的量子化学的高斯基方法。该技术同时解决了两个连续电子的处理问题和分子靶的初始和最终束缚电子的关联问题，并将用同样的方法处理强场中原子和分子的非顺序双光子双电离。提出了一种新的方法来解决这个问题，它可以完全描述氦和氢的双光子双电离。与这些理论预测一起，可以用现有仪器进行的新实验将能够回答关于这种基本强场过程的许多开放性问题。