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Electron interactions with small molecular clusters

电子与小分子簇的相互作用

基本信息

批准号：
EP/E001238/1
负责人：
Jimena Gorfinkiel
金额：
$ 19.48万
依托单位：
The Open University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FE001238%2F1
关键词：
Electron interactions small molecular clusters

项目摘要

Free electrons are present in many environments (the atmosphere, the outer space, irradiated cells, plasmas). Also present in these environments are atoms and molecules. The electrons can interact with the atoms and molecules and change direction or give up some of their energy; scientists call this process a collision. At the same time, the exchange of energy can modify the state of the molecules (excite them), or even break them into smaller molecules or atoms. Understanding these processes is very important for the understanding of the aforementioned environments. Knowledge of collisional information is required for many practical applications. For example, free electrons are present in the cells of living organisms if they receive radiation. It is now known that these electrons can break-up the DNA, damaging our bodies. But, fortunately, we can also use this interaction in a positive way. Cancer treatments based on radiotherapy make use of these processes to destroy cancerous cells. By understanding how electrons interact with the DNA, we can improve these treatments. Electron-molecule collisions also take place in astrophysical environments. It is though that the precursors of life (organic and biomolecules) may have been created in outer space due to the interaction of electrons with atoms and molecules. There are also technological applications for which the knowledge of the collisional process is important: the microchip industry makes use of electron-molecule collisions to generate radicals (very reactive molecular fragments) that react with a silicon oxide substrate thus etching a circuit on it. Scientists have studied collisions for many years, both by means of experiments and using theoretical models and computers. Many methods have been proposed, but due to the complexity of the processes, not many electron-molecule collisions have been studied properly from a theoretical point of view. To describe a collision correctly one has to be able to describe the molecule (the target) accurately and also its interaction with the projectile (the free electron). The bigger the target is (the more nuclei and electrons it has) the more difficult it is to describe its states properly: one needs to use good, accurate methods but also big, powerful computers in an efficient way. There is an additional complication when one studies collisions in the fields for which information on electron-molecule interactions is important: the molecules are not isolated. The electrons collide with molecules that are surrounded by other molecules or atoms (for example, in a cell there is plenty of water molecules). These surrounding particles can significantly affect the outcome of the collisions in many ways. Hence, it is important to think of models to incorporate these effects in the calculations. Clusters (groups of a few molecules) are somehow in between isolated molecules and solids and liquids. Because they involve fewer particles than the condensed phase, studying them is easier. These studies are a good starting point to develop methods to treat electron collisions with condensed molecules.Hopefully, this will help us to achieve a new level of understanding of electron-molecule process and will also provide us with the tools to investigate from the theoretical point of view a lot of processes that are very relevant in our lives nowadays.

自由电子存在于许多环境中（大气层，外层空间，辐照细胞，等离子体）。在这些环境中也存在原子和分子。电子可以与原子和分子相互作用，改变方向或放弃一些能量;科学家称这个过程为碰撞。同时，能量的交换可以改变分子的状态（激发它们），甚至将它们分解成更小的分子或原子。理解这些过程对于理解上述环境非常重要。碰撞信息的知识是许多实际应用所必需的。例如，如果生物体的细胞接受辐射，就会存在自由电子。现在我们知道，这些电子可以破坏DNA，损害我们的身体。但是，幸运的是，我们也可以以积极的方式利用这种互动。基于放射疗法的癌症治疗利用这些过程来破坏癌细胞。通过了解电子如何与DNA相互作用，我们可以改进这些治疗方法。电子-分子碰撞也发生在天体物理环境中。人们认为，生命的前体（有机分子和生物分子）可能是在外层空间由于电子与原子和分子的相互作用而产生的。碰撞过程的知识在一些技术应用中也很重要：微芯片工业利用电子-分子碰撞产生自由基（非常活泼的分子碎片），这些自由基与氧化硅衬底发生反应，从而在其上蚀刻电路。科学家们通过实验、理论模型和计算机对碰撞进行了多年的研究。人们已经提出了许多方法，但由于过程的复杂性，从理论的角度来看，并没有多少电子-分子碰撞得到适当的研究。为了正确地描述碰撞，人们必须能够准确地描述分子（目标）及其与抛射体（自由电子）的相互作用。目标越大（原子核和电子越多），正确描述其状态就越困难：人们需要使用好的、准确的方法，但也需要使用大而强大的计算机。当人们在电子-分子相互作用的信息很重要的领域研究碰撞时，还有一个额外的复杂性：分子不是孤立的。电子与被其他分子或原子包围的分子碰撞（例如，在细胞中有大量的水分子）。这些周围的粒子可以在许多方面显著影响碰撞的结果。因此，重要的是要考虑将这些影响纳入计算的模型。团簇（几个分子的组）以某种方式介于孤立的分子和固体与液体之间。因为它们比凝聚相包含更少的粒子，所以研究它们更容易。这些研究是发展处理电子与凝聚态分子碰撞的方法的一个很好的起点，希望这将有助于我们对电子-分子过程的理解达到一个新的水平，也将为我们提供工具，从理论的角度研究许多与我们当今生活非常相关的过程。