RAMAN SPECTROSCOPY/ SINGLE-MOLECULE IMAGING: CARS modification eliminates background noise in single-molecule images

A new imaging approach called vibrational molecular interferometry (VMI)—a modification of coherent anti-Stokes Raman spectroscopy (CARS)—eliminates the background noise that can make it difficult to interpret CARS images, according to researchers at the University of Twente's MESA+ Institute for Nanotechnology (Enschede, The Netherlands), who developed it.¹

Molecules in mayonnaise are depicted with (a) CARS spectroscopy and with (b) vibrational molecular interferometry (VMI), which displays less background noise. The graphs depict intensity along the white line that runs through the center of the picture. (Image courtesy of the University of Twente MESA+ Institute for Nanotechnology)

CARS uses lasers to visualize single molecules without the use of fluorescent labels. The Dutch researchers use the energy levels inside the molecules as their starting point. This makes it easier to detect the signature of the target molecule, the researchers say, and it allows access to more information than ever before, including as accurate details of the substance's concentration.

1. E.T. Garbacik et al., Phys. Rev. Lett., doi:10.1103/PhysRevLett.107.253902 (2011).

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