Single-Molecule Raman Spectroscopy

Single-molecule spectroscopy allows scientists to investigate properties of individual molecules or their reactions to reveal information that might be lost when averaged over an ensemble. Single-molecule experiments are commonly done by using techniques that generate strong signals, such as laser-induced fluorescence. Chemists would like to add other techniques that can yield additional chemical information. Now, a University of Tennessee, Knoxville, team led by Jon P. Camden has demonstrated single-molecule sensitivity for just such a technique: surface-enhanced hyper-Raman spectroscopy (J. Phys. Chem. Lett. 2013, DOI: 10.1021/jz4017415). Camden and colleagues tested the technique on crystal violet. On the basis of control tests, the team concludes that the method provides adequate resolution to record spectra of individual molecules. The approach should be useful for studying nonlinear properties of molecules, which are important for applications such as molecular switching.