Tip-Enhanced Raman Spectroscopy with Picosecond Pulses.
Tip-enhanced Raman spectroscopy (TERS) can probe chemistry occurring at surfaces with both nanometer spectroscopic and submolecular spatial resolution. Combining ultrafast spectroscopy with TERS allows for picosecond and, in principle, femtosecond temporal resolution. Here we couple an optical parametric oscillator (OPO) with a scanning tunneling microscopy (STM)-TERS microscope to excite the tip plasmon with a picosecond excitation source. The plasmonic tip was not damaged with OPO excitation, and TER spectra were observed for two resonant adsorbates. The TERS signal under ultrafast pulsed excitation decays on the time scale of 10 s of seconds; whereas with continuous-wave excitation no decay occurs. An analysis of possible decay mechanisms and their temporal characteristics is given.
Northwestern University, Department of Chemistry, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Jordan M
JM
Klingsporn
Northwestern University, Department of Chemistry, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Matthew D
MD
Sonntag
Northwestern University, Department of Chemistry, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Tamar
T
Seideman
Northwestern University, Department of Chemistry, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Richard P
RP
Van Duyne
kinetics; picosecond excitation; plasmonics; tip-enhanced raman spectroscopy; ultrafast raman spectroscopy