Institut Fresnel

Identify the good vibrations of molecules

Researchers at the Institut Fresnel in Marseille have developed an imaging technique to determine directly the organization of molecules in the material, and so reveal its structure at the molecular level. The measured signal is not only sensitive to the presence of the molecule but also specific in the way it vibrates, providing structural information previously untapped.

In an article published on 18 May 2016 in the journal Nature Communications, they describe how to shape the polarization of electromagnetic fields to specifically stimulate certain molecular vibrational modes. This method is based on the nonlinear coherent Raman process CARS (coherent anti-Stokes Raman scattering) and group theory concepts. Very simple to implement, this advanced technique is another step in label free microscopy. It offers new perspectives in biology and for biomedical diagnostics, areas where the optical microscope is an essential instrument.

Figure : Imaging of carbon-carbon bonds of myelin in a side section of spinal cord.
The circular structures correspond to the myelin sheaths surrounding the dendrites. The brightness of the image corresponds to the density of carbon-carbon bonds, the color scale corresponds to the organization of the bonds: the isotropic vibration are in red, the uni-directional vibration are in blue.
This image is obtained in a single acquisition without fluorescent probes, and thus allows to provide structural information on the organization of molecules in the sample (image 30 × 30 microns).

Référence
Carsten Cleff, Alicja Gasecka, Patrick ferrand, Hervé Rigneault, Sophie Brasselet et Julien Duboisset
“Direct imaging of molecular symmetry by coherent anti-Stokes Raman scattering”
Nature Communications 7, Article number 11562 (18 mai 2016)

Contacts
Institut Fresnel (CNRS UMR 7249), Marseille, France
www.fresnel.fr
Chercheur : Julien Duboisset, Maître de conférences à l’université Aix Marseille, Courriel : julien.duboisset@fresnel.fr, Tél. : 04 91 28 80 49
Chargée de communication : Claire Guéné, Courriel : claire.guene@fresnel.fr, Tél : 04 91 28 83 26