| The work presented in this dissertation involves the study of the interface of organic thin films using SFG and the construction and development of a new SFG microscope combining a novel sampling theorem, compressive sensing (CS).;Interfacial properties of various SAMs containing ethylene glycol (EG) units on gold were also explored using the nonlinear optical technique, SFG. The fundamental studies of the interfacial conformation of the EG SAMs provided insight into understanding the mechanism of the protein resistance of the EG monolayers. New details were revealed for the monofunctional and difunctional poly (ethylene glycol) (PEG) thiolate SAMs. The results also showed that odd or even number of aliphatic CH2 units affected the interfacial conformation of the five-member ring EG monolayers.;A new SFG microscope using a novel sampling theory, CS, was successfully constructed and developed to obtain two-dimensional chemical contrasts for surfaces. The advantages of the SFG-CS microscope over the traditional SFG microscopes include the capability of imaging monolayers on dielectric substrate, fewer measurements required for reconstructing a good quality image, high signal to noise ratio (SNR), allowing the use of a "single pixel" detector, for example photomultiplier tube (PMT), low cost, and higher sensitivity.;Spatial chemical contrast of the trichlorooctadecane silane SAM on glass substrate was successfully obtained using the SFG-CSM. A gold pattern with stripes was used to characterized the microscope and examine the influence of CS parameters and operation conditions on the quality of the images. Comparison of the new SFG-CS method and the traditional raster scanning was also made.;The surface barrier properties of the alkanethiol self-assembled monolayers (SAMs) with varying chain lengths were deduced using SFG combined with electrochemical methods, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicated that the long chain SAMs could act as dual role corrosion inhibitors, the cathodic/anodic inhibitor, and the barrier inhibitor. |
