Sum frequency generation imaging with spectroscopic vibrational contrast is a label-free solution for visualizing, identifying, and quantifying a wide range of chemical properties of metal Surfaces.  In the practical applications, the fast imaging capabilities is always comprised with the loss of spectroscopic information over a broad spectral bandwidth. Compressive sampling is a new method to capture and represent compressible signals at a rate significantly below the Nyquist rate; the signal is then reconstructed from these projections using an optimization process. Our novel technique has combined the Compressivesampling theory with Sum frequency generation imaging to address the current technique challenges in real time chemical diagnostics capabilities. We have applied this novel technique to real time monitor the formation of a thin oxide film on both octadecanethiol (ODT) deposited copper and chemically stripped copper surface. The spontaneous atmospheric oxidation of Cu from an initial reduced state was observed as a change in the non-resonant phase response of the sum frequency generation (SFG) spectral line shape obtained. Over the exposure time, these different regions were observed to gradually undergo Cu oxidation. This finding has a significant contribution toward recognizing that metal surface protection and corrosion.

Compressive sensing sum-frequency-generation microscopy real-time monitoring copper oxidation

248th National Meeting (2014)

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