FOR 1789: Intermolecular and Interatomic Coulombic Decay

1789 年：分子间和原子间库仑衰变

• 批准号: 203306641
• 金额: --
• 依托单位: Fritz-Haber-Institut der Max-Planck-Gesellschaft (FHI)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/203306641?language=en
• 关键词: 1789; Intermolecular; Interatomic; Coulombic; Decay

Chemical reactions and modifications of molecular structure are driven by energy. Often, this energy exists initially in the form of electronic excitations. The relaxation of electronically excited states is therefore a key question in chemistry and molecular biology. The topic of this Research Unit is the investigation of a novel, recently discovered mechanism for the transformation of electronic energy created by excitation or ionisation with UV radiation and far beyond, or energetic particles. This relaxation process has become known as Intermolecular or Interatomic Coulombic Decay (ICD). The term designates an electronic decay process occurring in weakly bonded systems, for example in many liquids. Via ICD, electronic excitation energy is transferred into kinetic energies carried by a continuum electron and the creation of two positive ions. The conditions for the occurrence of ICD are very general; it is expected they are met in many systems and situations. The first step in ICD is the creation of a single electronic vacancy, the energy of which is located above the double ionisation threshold of the weakly bonded system as a whole. An example is the ionisation of an inner valence level in water. Although such processes have been investigated for a long time, it has been predicted only in 1997 that neighbouring water molecules could be involved in the relaxation of such a vacancy. In the Intermolecular Coulombic Decay process, this primary vacancy is filled by an electron from a less strongly bound orbital, and at the same time the energy released in this transition is transferred to a neighbouring molecule, where it leads to ejection of an electron. Putting ICD in a broader context, it bridges the gap between fundamental research on the correlated motion of electrons and nuclei and more applied research, for example, on the influence of low kinetic energy electrons in radiation chemistry. The Research Unit aims to answer key questions in connection with our understanding of ICD: (1) Which physical and chemical parameters have the strongest influence on the ICD process? (2) In which systems will ICD occur? (3) In which areas of chemistry is ICD of importance? How can it be employed as a method in chemical research? (4) Does ICD have biochemical implications, e.g., in the production of radiation damage? (5) What is the time evolution of ICD?

化学反应和分子结构的修饰是由能量驱动的。通常，这种能量最初以电子激发的形式存在。因此，电子激发态的放松是化学和分子生物学的关键问题。该研究单位的主题是研究一种新颖的，最近发现的机制，用于转化由紫外线辐射和远远超出或能量颗粒的激发或电离产生的电子能量。这种放松过程已被称为分子间或原子间库仑衰减（ICD）。该术语指定了在弱键系统中发生的电子衰减过程，例如在许多液体中。通过ICD，将电子激发能传递到连续电子携带的动能和两个正离子的产生中。 ICD发生的条件非常笼统。预计在许多系统和情况下都可以满足它们的需求。 ICD中的第一步是创建单个电子空缺，其能量位于整个弱键系统的双电离阈值上方。一个例子是水中内价水平的电离。尽管已经研究了很长时间，但仅在1997年才预测，邻近的水分子可能与这种空缺的放松有关。在分子间库仑衰减过程中，该主要空缺由一个从不太结合的轨道上的电子填充，与此同时，该过渡中释放的能量被转移到邻近的分子中，从而导致电子的弹射。将ICD放置在更广泛的背景下，它弥合了关于电子和核的相关运动的基本研究与更多应用研究的基本研究，例如，低动能电子在辐射化学中的影响。研究部门旨在回答与我们对ICD的理解有关的关键问题：（1）哪些物理和化学参数对ICD过程的影响最大？ （2）在哪种系统中发生ICD？ （3）在哪个化学领域重要的ICD重要性？如何用作化学研究方法？ （4）ICD是否具有生化含义，例如在产生辐射损害中？ （5）ICD的时间演变是什么？