—A Fast, Coherent Look At Single-Molecule Vibrations “Coherent anti-Stokes Raman-scattering signals, acquired in femtoseconds, don’t dephase like ensemble measurements” Ultrafast nonlinear spectroscopy in which scientists excite a molecule with optical pulses and then use a probe pulse to see what happens allows researchers to observe the motions of chemical bonds. But such measurements are usually made of large ensembles of molecules and are limited to timescales over which the molecular motions of the ensemble remain coherent. Vartkess A. Apkarian, Eric O. Potma, and coworkers at the University of California, Irvine, show that they can now make measurements of single molecules by attaching the molecules to dumbbell-shaped silica-coated gold “nanoantennae” and using surface-enhanced coherent anti-Stokes Raman scattering, or CARS (Nat.
by Celia Henry Arnaud |
July 14, 2014