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G. Rupprechter:
"Sum Frequency Generation Spectroscopy and Second Harmonics Generation";
in: "Reference Module in Chemistry, Molecular Sciences and Chemical Engineering", issued by: Jan Reedijk; Elsevier Inc., Oxford, United Kingdom, 2017, (invited), 1 - 11.

The function of modern materials or devices is often governed by processes occurring at nanoscale interfaces, the characterization of which requires utmost surface sensitivity. Sum frequency generation (SFG) laser spectroscopy is an inherently interface-specific nonlinear optical method that allows examining vibrational modes of molecules located at solid-gas or solid-liquid interfaces. Provided the interface is accessible to infrared and visible light, SFG allows identifying chemical species adsorbed on single crystals, thin films, and nanoparticles of various materials, including metals, oxides, carbon, etc. Furthermore, molecular densities, orientations, and dynamics can be addressed. Combining the selection rules of infrared and Raman, SFG is insensitive to bulk or isotropic phases, enabling to study processes under technologically relevant conditions, such as high gas pressure or in liquid, which, for other methods, often obscures the interface information.

The different modes of SFG operation, such as scanning, broadband, time-resolved, and polarization-dependent, have been applied to various fields of interfacial chemistry, for example, surface and materials science (including catalysis, electrochemistry, photochemistry, sensors, tribology, polymers, biomembranes, etc.). Fundamentals and technical aspects of SFG are summarized and illustrated by selected case studies.

Broadband SFG; High pressure reaction cell; Laser spectroscopy; Molecular dynamics; Molecular orientation; Nonlinear optical spectroscopy; Polarization-dependent SFG; Solid-liquid; Solid-gas; Sum frequency generation; Surface sensitivity; Time-resolve

http://dx.doi.org/10.1016/B978-0-12-409547-2.12825-2