Coupled wave equations theory of surface-enhanced femtosecond stimulated Raman scattering.
We present a coupled wave semiclassical theory to describe plasmonic enhancement effects in surface-enhanced femtosecond stimulated Raman scattering (SE-FSRS). A key result is that the plasmon enhanced fields which drive the vibrational equation of motion for each normal mode results in dispersive lineshapes in the SE-FSRS spectrum. This result, which reproduces experimental lineshapes, demonstrates that plasmon-enhanced stimulated Raman methods provide unique sensitivity to a plasmonic response. Our derived SE-FSRS theory shows a plasmonic enhancement of |gpu|(2)ImχR(ω)gst (2)/ImχR(ω), where |gpu|(2) is the absolute square of the plasmonic enhancement from the Raman pump, χR(ω) is the Raman susceptibility, and gst is the plasmonic enhancement of the Stokes field in SE-FSRS. We conclude with a discussion on potential future experimental and theoretical directions for the field of plasmonically enhanced coherent Raman scattering.
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
Michael O
MO
McAnally
Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164-2814 USA.
Jeffrey M
JM
McMahon
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
Richard P
RP
Van Duyne
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
George C
GC
Schatz