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MO: Fachverband Molekülphysik

MO 18: Experimentelle Techniken

MO 18.3: Talk

Thursday, March 5, 2009, 11:15–11:30, VMP 6 HS-F

Broadband Multiplex-CARS-Microscopy in forward and backward detection with application in material and biological science — •Christoph Pohling, Alexander Southan, and Marcus Motzkus — Philipps-Universität, Physilkalische Chemie, D-35043 Marburg

We implemented Multiplex coherent anti-Stokes Raman scattering (MCARS) as a labelling free technique in nonlinear microscopy in a commercially available Phase-Contrast microscope acquiring vibrational spectra covering a range of more than 3000 wavenumbers. Since the signal can be detected in forward and backward direction, this technique also matches for non transparent samples. Compared to the previous setup, the lateral and spectral resolution was improved. We carefully studied the influence of collimation of Pump and Stokes as well as beam diameters, microscope objective types and aperture sizes to optimize the spatial resolution in axial direction. The spectral resolution required balancing between narrowband-filtration of the Pump beam and the loss of signal intensity. With the optimised Setup which just uses a traditional Ti:Sa fs-oscillator, we are able to study a film consisting of several layers of different polymers with a thickness of 1-3 *m each by raster scanning the sample in Z-direction. The chemical composition, position and thickness of each layer could be retrieved from the MCARS-data. Concerning biological components cells of moss and porcine brain tissue also led to MCARS-pictures. Finally, the surface of writing paper was scanned in a first approach of three-dimensional imaging.