Collision-induced few-body dynamics of atomic and molecular systems

点击翻译按钮获取中文摘要

Atoms and molecules are objects of the quantum world. Given that the basic laws of quantum mechanics have been known since the 1920s, one might think that atomic and molecular structure and dynamics are well understood by now and can be calculated, using those laws, to any desired level of accuracy. This is not the case. When it comes to dynamics, exact solutions of the known equations are not feasible, except for the simplest situations, and they will not be feasible for some time to come despite the ever-increasing availability of computational resources. At the heart of the matter lies the complexity of the quantum-mechanical few-body problem, and on a fundamental level, it is the interest in this problem that drives this research program. We will study quantal few-body dynamics by looking into collisions of ions with atoms and molecules and solving simplified versions of the fundamental equations that govern the collisional interactions. These simplified equations are still far to complex to be solved in pen and paper form. Accordingly, we will develop algorithms and computer programs to obtain numerical solutions. Comparing them with experimental data will shed light on the quantum dynamics at play and on the usefulness and the limitations of our methods, thereby advancing our understanding of the quantum-mechanical few-body problem. Our studies will also benefit the experimentalists working in this area. They will assist them in interpreting their data and guide them in the design of future experiments. For example, recent ionization measurements of lithium atoms have raised the question whether certain processes which involve two of the three lithium electrons contribute to the measured spectra. We plan to study the role and the nature of these processes. One question our calculations will address is whether they are dominated by independent interactions of the impinging ion with each electron, or if the interaction between the electrons is important as well. The latter interaction is associated with so-called electron-correlation effects, which play a central role in many atomic, molecular and condensed-matter systems and give rise to such interesting phenomena as superconductivity. Our work will also have significant applications. A major goal of this research program is to push our methods to make them applicable to collisions involving organic molecules. This will be relevant for the field of radiobiology. When biological tissue is irradiated by protons or heavy ions, electrons are set free and the ionized molecules may break apart. In tumour radiation therapy this contributes to the desired destruction of the tumour and to the undesired destruction of the surrounding tissue. Understanding the problem of radiation damage on a fundamental level requires the detailed analysis of the underlying collision processes. This is what our research is concerned with. In the long term it will benefit the complex field of damage to large molecules such as DNA bases and will potentially have some societal impact in that its outcomes may contribute to a more successful treatment of cancer.