Optical techniques enable examination of single molecules, but fuzziness caused by effects such as light interference render these images difficult to interpret. Recognizing this, researchers at the University of Twenteâs MESA+ Institute for Nanotechnology (Enschede, The Netherlands) adopted a "reverse" approach to spectroscopy, which cleans up images by eliminating background noise.
Rather than starting with a laser beam, the researchers used molecules of interest as their starting point. This radical "reversal" led to a relatively simple modification of conventional coherent anti-Stokes Raman spectroscopy (CARS), which delivered better images. CARS uses lasers to visualize molecules for applications such as medical imaging and food testing, without needing fluorescent labels to make the molecules visible. But background noise complicates the task of interpreting the resultant images. The researchers' new approachâvibrational molecular interferometry (VMI)âeliminates such noise completely, leaving only the "real" image.
|Images of mayonnaise using a) CARS spectroscopy and b) vibrational molecular interferometry (VMI). Below, the intensity along the white line in the picture is given. Using VMI, the background signal vanishes. (Image courtesy of University of Twente MESA+ Institute for Nanotechnology)|
The researchers' work has been published in Physical Review Letters; for more information, please visit http://prl.aps.org/abstract/PRL/v107/i25/e253902.
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