The Development and Applications of Nonlinear Vibrational Spectroscopy for Material and Biological Studies.

Abstract

Nonlinear vibrational spectroscopy has been extensively developed and has found important applications in recent years. As a label free technique, vibrational spectroscopy has great advantages in material science, analytical chemistry and biological engineering. The theoretical and technical development, as well as application approaches in nonlinear vibrational spectroscopy can help to push this field towards a more prosperous future. The goal of this thesis is to demonstrate my personal contributions in these three directions of nonlinear vibrational spectroscopy. We mainly focused on a second order nonlinear spectroscopy sum frequency generation (SFG), and a third order nonlinear spectroscopy coherent anti-Stokes Raman scattering (CARS), supplemented by a linear attenuated total-internal reflection Fourier transformation IR (ATR-FTIR) spectroscopy and other techniques. The research focus of this thesis can be summarized in four parts: (1) the applications of SFG spectroscopy in understanding interfacial molecular structures of various adhesive materials, more specifically silicone and epoxy adhesives, to elucidate their adhesion mechanisms to different substrates; (2) the applications of SFG spectroscopy supplemented by ATR-FTIR spectroscopy for studying lipid dynamics in supported lipid bilayers used to mimic biological membranes, as well as elucidating cytotoxicity mechanisms of a certain polyelectrolyte; (3) the technical development of new analytical platforms to integrate SFG spectroscopy with other optical techniques (including CARS, optical microscopy or total-internal reflection fluorescence (TIRF) microscopy) for multimodal sample studies; (4) the quantitative interpretation of the spectral measurements in CARS spectroscopy with the help of bond additivity method and Raman depolarization ratio, which has significance in quantitative spectral analysis in modern CARS spectroscopy and microscopy. The theoretical advancement, technical development and extensive applications of SFG and CARS spectroscopy demonstrated in this thesis can help to improve nonlinear spectroscopy to be a more powerful and versatile tool in material science, biology, or other industry-driven interdisciplinary fields.