Ultrafast gas phase dynamics of isolated and solvated anions: Complex anions in chemistry and biology

大多数化学和生物学都是在溶液中发生的，无论是在锥形烧瓶中还是在我们的人体中。在溶液中，带电粒子或离子起着关键作用。它们的电荷允许它们与周围的溶剂发生非常强烈的相互作用，这通常导致它们相对于完全分离的（气相）离子的性质发生重大变化。这个建议涉及这些离子的研究及其在溶剂化时的变化，一次一个溶剂分子。具体来说，高度复杂的负离子（阴离子），包括多电荷和大的生物感兴趣的阴离子将被研究。特别令人感兴趣的是这些复合阴离子对光源的反应。在适当波长照射后，阴离子分子内可发生许多过程。这包括：解离，离子分解；剥离：从阴离子上剥离一个电子（电荷）；还有分子重排，阴离子分子中的原子重新组织自己。这些过程发生的时间在几十到几百飞秒的数量级上，比一秒短10,000,000,000,000 ！幸运的是，有一些激光可以产生如此短的光爆发，因此我们可以使用这些激光来启动一个分子过程，并使用第二次爆发来监测由第一次启动的过程。因为激光闪光比分子过程要短，所以在闪光灯打开和关闭的时间内，分子框架内的原子位置基本上是“冻结”的，它实际上就像相机上的快门。通过这种方式，我们可以通过在过程启动后的不同时间拍摄这些快照来拍摄随后的过程，从而建立一个完整的分子动力学图像。这些动力学研究将在分离的阴离子和被一、二、三等溶剂分子溶剂化的相同阴离子上进行。研究孤立的复合阴离子是普遍感兴趣的，因为对它们的了解相对较少，而且它们作为孤立物种进行研究的细节远远超过了溶液中相同离子的细节，因为溶剂模糊了大部分信息。溶剂的添加，一个接一个，将揭示溶剂的作用。每加入一个溶剂分子，就会使这个系统更接近于化学烧瓶或我们人体中的情况，这样我们就可以看到从一个孤立的离子到溶液中相同离子的转变。

Most chemistry and biology occurs in solution, be it in a conical flask or our human body. In solutions, charged particles, or ions, play a pivotal role. Their charge allows them to interact very strongly with the surrounding solvent, which often leads to a significant change in their properties relative to completely isolated (gas-phased) ions. This proposal concerns the study of these ions and their change upon solvation, one solvent molecule at a time. Specifically, highly complex negatively charged ions (anions), including multiply charged and large biologically interesting anions will be studied.Of particular interest is the response of these complex anions to a light source. Following irradiation of a suitable wavelength, many processes may occur within the anionic molecule. These include: dissociation, in which the ion falls apart; detachment in which one electron (charge) is removed from the anion; and molecular rearrangement, in which the atoms within the anionic molecule reorganise themselves. The time in which these processes occur is on the order of tens to hundreds of femtoseconds, which is 10,000,000,000,000 shorter than a second! Luckily, there are lasers that can produce bursts of light that are this short and thus we may use these lasers to initiate a molecular process and use a second burst to monitor the process initiated by the first. Because the laser flash is shorter than the molecular process, the atomic positions within the molecular framework are essentially 'frozen' over the time in which the flash comes on and off / it effectively acts as a shutter on a camera. In this manner, we may take snap-shots of the ensuing process by taking these snap-shots at various times after the process was initiated and thus built a complete picture of the molecular dynamics.These dynamical studies will be carried out on both the isolated anion and on the same anion solvated by one, two, three, and so on, solvent molecules. Studying the isolated complex anion is of general interest because relatively little is understood about these, and the detail in which they can be studied as isolated species vastly exceeds that of the same ion in a solution, because the solvent blurs much of the information. Addition of solvent, one by one, will reveal the role of the solvent. Every addition of a solvent molecule will bring the system that little closer to the situation in a chemical flask or our human body and so we may view the transition from an isolated ion to the same ion in solution.