Time-Resolved Measurement of Vibrational Coherences in the Single Molecule Limit
- Author(s): Yampolsky, Steven
- Advisor(s): Apkarian, Vartkess A
- et al.
Time-resolved, surface-enhanced, coherent anti-Stokes Raman spectroscopy (tr-SECARS) is
ideally suited for preparing and interrogating vibrational coherences on single molecules.
We have succeeded in the rst demonstration of this concept through measurements carried
out on molecules attached to gold nanosphere pairs which act as plasmonic nano-dumbell
antennae. The tr-SECARS traces provide unique signatures of coherent evolution in discrete
ensembles. The signals are characterized by phase and amplitude noise, which can be cast in
terms of amplitude probability distribution functions (PDF), which allow rigorous distinction
between single, few, and many molecule coherences. We give a brief background on tr-CARS,
the experimental system for carrying out tr-SECARS and the analysis of the results in terms
of PDFs. The analysis makes it clear that we have, for the rst time, observed the coherent
vibrational motion of a single molecule.