Molecular-LevelSurface Structure from Nonlinear VibrationalSpectroscopy Combined with Simulations.

Vibrationalsum-frequency generation spectroscopy is valued forits ability to selectively probe molecules at a variety of interfaceswithout the use of extrinsic chromophores. The spectra contain valuableinformation regarding the molecular structure and the interfacialenvironment through the observation of vibrational resonances associatedwith specific moieties. Chemical information is obtained by closeinspection of the frequencies of these bands and the amplitude ofthe response under conditions of different beam polarizations. Suchsensitivity motivates the development of techniques that can providestructural details. We illustrate several approaches by which varioustypes of calculations and molecular simulations may be used to enhancethe sought structural interpretation of experimental data. By applyingthese techniques to the adsorbate molecules, interfacial water, andthe substrate surfaces themselves, we are able to achieve a holisticpicture of the adsorption environment. [ABSTRACT FROM AUTHOR]