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Solvent Effects for Vertical Ionization Processes in Liquid Water and at the Liquid-Vapor Interface

Coons, Marc P. L.
http://orcid.org/0000-0001-9511-2854
http://rave.ohiolink.edu/etdc/view?acc_num=osu1503014629752161

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Chemistry.
Liquid microjet photoelectron spectroscopy is a state-of-the-art experimental technique that provides avenues for investigating ultrafast charge and energy transfer processes in liquid water and aqueous solutions. The emphasis of this work is placed on making contact with recent liquid microjet experiments of hydrated electrons, e-(aq), in liquid water and at the liquid-vapor interface from a computational perspective. Since its discovery nearly 55 years ago, e-(aq) has attracted significant attention from both experimental and theoretical communities due to its crucial role in radiation chemistry and its relatively elusive structure in liquid water at ambient conditions. Historically, the primary observable of hydrated electrons has been a well-characterized optical absorption spectrum, but with the advent of liquid microject spectroscopy, this has shifted to measurements of its relative binding energy below vacuum level. Some experiments utilizing this methodology have been interpreted to suggest that e-(aq) at the liquid-vapor interface is energetically dissimilar than in liquid water, and that, unlike the more strongly bound species in liquid, it can potentially undergo destructive reactions with solvated DNA molecules. A variety of computational strategies are employed to demonstrate that the spectroscopic properties of hydrated electrons in liquid water are actually quite similar to the interfacial species. To that end, mixed quantum-classical molecular dynamics simulations are performed where e-(aq) in liquid water and at the interface is described by two different one-electron pseudopotentials. These simulations suggest that the presence of e-(aq) at a liquid-vapor interface is fleeting at ambient conditions, and to experimentally distinguish it from the bulk species using standard spectroscopic techniques would be challenging. Non-equilibrium polarizable continuum models (PCMs), in conjunction with MP2 and DFT methods, are then employed to compute vertical ionization energies in liquid water. However, computing these quantities in anisotropic environments, such as at an interface, is not possible with traditional PCMs. Therefore, a novel methodology is presented for computing vertical ionization energies at a liquid-vapor interface that has developed to incorporate non-equilibrium solvent polarization effects for molecules immersed in arbitrary dielectric environments. This method is applied to e-(aq), alkali metal cations, and halide anions in liquid water, for which vertical ionization energies have been measured, and also to predict these quantities at the interface where some liquid microjet measurements do not yet exist.
John Herbert, Ph.D. (Advisor)
James Coe, Ph.D. (Committee Member)
Sherwin Singer, Ph.D. (Committee Member)
Laura Podalsky, Ph.D. (Committee Member)
198 p.
Chemistry; Physical Chemistry
hydrated electrons; alkali metal cations; halide anions; vertical electron binding energy; vertical ionization potential; continuum solvation models; DFT; MP2; mixed quantum-classical simulations; multigrid method

Recommended Citations

Citations

  • Coons, M. P. L. (2017). Solvent Effects for Vertical Ionization Processes in Liquid Water and at the Liquid-Vapor Interface [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503014629752161

    APA Style (7th edition)

  • Coons, Marc. Solvent Effects for Vertical Ionization Processes in Liquid Water and at the Liquid-Vapor Interface. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1503014629752161.

    MLA Style (8th edition)

  • Coons, Marc. "Solvent Effects for Vertical Ionization Processes in Liquid Water and at the Liquid-Vapor Interface." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503014629752161

    Chicago Manual of Style (17th edition)

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