The last decade has seen a resurgent interest in the exploration and utilization of multiphoton processes.  Two photon transitions, for example, play critical roles in all-optical switching, biological imaging, and drug delivery via two-photon cleavable lipids.  The intersection, however, of higher-order spectroscopies with the emerging field of plasmonics is an unexplored frontier.  Therefore, we have undertaken a systematic study of surface enhanced hyper-Raman scattering (SEHRS), which serves as a prototypical surface enhanced nonlinear spectroscopy.  SEHRS demonstrates the ability to probe �dark� electronic states, i.e. those that are inaccessible via one-photon excitation, with extreme sensitivity (~10-10 M).  It further provides a method to probe the properties of nonlinear chromophores.  Such studies have highlighted the importance of non-Condon scattering and suggest new ways to optimize the nonlinear properties of molecules.

Surface enhanced nonlinear spectroscopy: Understanding two-photon molecular properties

245th National Meeting (2013)

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