Graduation Year

2005

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Chemistry

Major Professor

Brian Space.

Keywords

Water, Molecular dynamics, Liquid/vapor interface, Nonlinear spectroscopy, SFG

Abstract

Our work investigates theoretical approximations to the interface specific sum frequency generation (SFG) spectra at aqueous interfaces constructed using time correlation function (TCF) and instantaneous normal mode (INM) methods. Both approaches lead to signals in excellent agreement with experimental measurements. This work demonstrates how TCF and INM methods can be used in a complementary fashion to describe interfacial vibrational spectroscopy. Our approach is to compare TCF spectra with experiment to establish that our molecular dynamics (MD) methods can reliably describe the system of interest. We then employ INM methods to analyze the molecular and dynamical basis for the observed spectroscopy. We have been able to elucidate, on a molecularly detailed basis, a number of interfacial line shapes, most notably the origin of the complex O-H stretching SFG signal, and the identity of several intermolecular modes in the SFG spectra for the water/vapor interface.

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