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

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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.