title: Surface-Enhanced Femtosecond Stimulated Raman Spectroscopy.
abstract: Surface-enhanced Raman spectroscopy (SERS) and femtosecond stimulated Raman spectroscopy (FSRS) have revolutionized the Raman spectroscopy field. SERS provides spectroscopic detection of single molecules, and FSRS enables the acquisition of Raman spectra on the ultrafast time scale of molecular motion. Here, we present the first successful combination of these two techniques, demonstrating surface-enhanced femtosecond stimulated Raman spectroscopy (SE-FSRS) using gold nanoantennas with embedded reporter molecules. Using a picosecond Raman and femtosecond probe pulse, the time- and ensemble-averaged enhancement factor is estimated to be in the range of 10(4)-10(6). We report the line shapes, power dependence, and magnitude of the SE-FSRS signal and discuss contributions to sample degradation on the minute time scale. With these first successful proof-of-principle experiments, time-resolved SE-FSRS techniques can now be rationally attempted with the goals of investigating the dynamics of plasmonic materials as well as examining the contributions of environmental heterogeneities by probing more homogeneous molecular subsets.
authors: Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors: Renee R
authors: RR
authors: Frontiera
authors: Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors: Anne-Isabelle
authors: AI
authors: Henry
authors: Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors: Natalie L
authors: NL
authors: Gruenke
authors: Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors: Richard P
authors: RP
authors: Van Duyne
keywords: FSRS; SERS; enhancement factor; femtosecond stimulated Raman spectroscopy; gold nanoparticle; surface-enhanced raman scattering; ultrafast vibrational spectroscopy