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Laser Spectroscopy

A signal boost for molecular microscopy

München, 07/12/2016

Physicists at LMU and the Max Planck Institute for Quantum Optics have developed a new technique based on cavity-enhanced Raman scattering, which provides information on the structure and properties of carbon nanotubes.

Schematic illustration of the experiment (MPQ, Laser Spectroscopy Division)

Carbon nanotubes can be produced with a variety of properties and in diverse shapes, and are therefore of interest for a range of applications in fields as diverse as electronics, photonics, nanomechanics, and quantum optics. Hence it is important to have a tool to hand that allows one to determine these properties rapidly and precisely. Raman spectroscopy is a particularly sensitive probe for the chemical structure that gives rise to these properties. However, the signals are intrinsically weak and call for enhancement techniques. Now, a team of researchers led by Nobel Laureate Theodor W. Hänsch, who holds a Chair in Experimental Physics at LMU and is a Director of the Max Planck Institute of Quantum Optics, has developed a method in which an optical microcavity is used to amplify Raman scattering signals, and utilized it for molecular diagnostics by combined Raman and absorption imaging. In contrast to other procedures, the new approach relies only on increased vacuum fluctuations of the electromagnetic field inside a cavity, which permits significant enhancement of the signal without adding undesired background. These features make the new technique a promising tool for molecular imaging. (Nature Communications, 12 July 2016)

Press release of the Max Planck Institute of Quantum Optics