Selective Probing of Thin Film Interfaces Using Internal Reflection Sum-Frequency Spectroscopy




Azam, Md. Shafiul
Cai, Canyu
Hore, Dennis K.

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The Journal of Physical Chemistry C


The study of interfacial properties of thin films such as polymers is an important area of surface science. The application of visible–infrared sum-frequency generation spectroscopy to such systems requires a careful interpretation of the results, as the electric field magnitude and phase at each interface must be determined in a manner that takes thin-film interference effects into account. Several schemes have been proposed for handling the local field corrections, and these methods all have their origins in linear optics. We first provide an extensive discussion of the cases in which the film is sufficiently thick that multiple beam interference can be ignored or sufficiently thin in which the relevant expressions collapse to simple forms. Then, we illustrate a straightforward method that has a concise analytic solution in the case of a single thin film that exhibits interference effects. We demonstrate a visualization technique that allows the experimental geometry to be tuned to select the interface of interest and rapidly switch between the interfaces when the film thickness is chosen to accommodate this.



Thickness, Thin films, Interfaces, Nonlinear optics, Infrared light


Azam, M. S.; Cai, C.; & Hore, D. K. (2019). Selective probing of thin-film interfaces using internal reflection sum-frequency spectroscopy. The Journal of Physical Chemistry C, 123(38), 23535-23544. DOI: 10.1021/acs.jpcc.9b06761