Collision- and laser-induced few-body dynamics in atomic and molecular systems

原子和分子系统中碰撞和激光诱导的少体动力学

• 批准号: RGPIN-2019-06305
• 负责人: Kirchner, Tom
• 金额: $ 2.04万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=738829
• 关键词: Collision; laser; induced; few; body

When an atom or a molecule is hit by an energetic ion or is exposed to a strong laser field it may release one or several of its electrons. In the case of a molecular target, this process of ionization may be followed by the break-up of the system into neutral and charged fragments which, similarly to the released electrons, may cause further ionization in surrounding matter. These processes are at the heart of the problem of radiation damage of biological tissue. Their quantitative understanding is the principal objective of this research program. Atoms and molecules follow the laws of quantum physics. When they are exposed to strong fields, either through collisional interactions or by laser illumination, the equations derived from those laws to describe their behaviour are so complex that exact solutions are not feasible. Models, advanced theoretical methods and numerical techniques are then required to make predictions on measurement outcomes or to produce numerical data that can be compared with available measurements to help understand the underlying physics and draw conclusions with regard to possible applications. The work described in this proposal is concerned with the development and execution of such models, methods and techniques. Two avenues of research will be pursued. On a fundamental level, we will use atomic collision problems as test beds for the further development of the so-called time-dependent density functional theory (TDDFT) approach, which is one of only a few theoretical methods available for describing collisional and laser-driven many-electron dynamics on a first-principles basis. We will implement a TDDFT scheme on a higher level of approximation than reported before and carry out numerical calculations for ion-atom collisions to help validate and improve the approach. We will also address an outstanding fundamental TDDFT problem related to the calculation of observable quantities. Our work will advance theory and produce data of interest to experimentalists in the field and to researchers in neighbouring disciplines who are, e.g., analyzing X-ray spectra of astrophysical objects or diagnosing high-temperature plasmas in the context of nuclear fusion experiments. On the more applied side we will study ion collisions from biologically relevant molecules, such as DNA/RNA building blocks, by elaborating on a simplified model description which we have proposed recently. Full first-principles calculations are not feasible for these complicated systems, yet reliable theoretical data would be important for an in-depth understanding of the problem of radiation damage of biological tissue. Our research is aimed at filling this void and producing such data. The results of our model calculations will benefit the field of radiobiology and, potentially, have an impact on clinical applications such as tumour therapy with positively-charged ions, thereby contributing to a more successful treatment of cancer.

当一个原子或分子被高能离子击中或暴露在强激光场中时，它可能会释放出一个或几个电子。在分子靶的情况下，该电离过程之后可以是系统分裂成中性和带电碎片，这些碎片类似于释放的电子，可以在周围物质中引起进一步电离。这些过程是生物组织辐射损伤问题的核心。对它们的定量理解是本研究计划的主要目标。 原子和分子遵循量子物理定律。当它们暴露在强磁场中时，无论是通过碰撞相互作用还是通过激光照射，从这些定律导出的描述它们行为的方程都是如此复杂，以至于精确的解是不可行的。然后，需要模型、先进的理论方法和数值技术来预测测量结果，或者产生可以与现有测量结果进行比较的数值数据，以帮助理解潜在的物理学并得出关于可能应用的结论。本提案所述的工作涉及开发和执行此类模型、方法和技术。将采取两种研究途径。在基本层面上，我们将使用原子碰撞问题作为进一步发展所谓的含时密度泛函理论（TDDFT）方法的试验台，这是仅有的几种理论方法之一，可用于描述碰撞和激光驱动的多电子动力学的第一性原理的基础上。我们将在比以前报道的更高的近似水平上实现TDDFT方案，并对离子-原子碰撞进行数值计算，以帮助验证和改进该方法。我们还将解决一个悬而未决的基本TDDFT问题有关的可观测量的计算。我们的工作将推进理论，并为该领域的实验人员和邻近学科的研究人员提供感兴趣的数据，例如，分析天体的X射线光谱或诊断核聚变实验中的高温等离子体。在更应用的一面，我们将研究离子碰撞从生物相关的分子，如DNA/RNA积木，通过详细说明我们最近提出的简化模型描述。完整的第一性原理计算对于这些复杂的系统是不可行的，然而可靠的理论数据对于深入理解生物组织的辐射损伤问题是重要的。我们的研究旨在填补这一空白，并产生这样的数据。我们的模型计算结果将有利于放射生物学领域，并可能对临床应用产生影响，例如使用带正电荷的离子进行肿瘤治疗，从而有助于更成功地治疗癌症。