Graduation Year


Document Type




Degree Granting Department


Major Professor

Brian Space, Ph.D.

Committee Member

Randy Larsen, Ph.D.

Committee Member

David Merkler, Ph.D.

Committee Member

David Rabson, Ph.D.


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


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. The success of both approaches suggests that theory can play crucial role in interpreting SFG spectroscopy at more complex interfaces.