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MO: Molekülphysik

MO III: HV III

MO III.1: Invited Talk

Tuesday, March 23, 2004, 12:00–12:30, HS 332

High spectral resolution non-linear optical microscopy with chirped, broad-band femtosecond pulses — •Andreas Zumbusch, Thomas Hellerer, Annika Enejder, and Ondrej Burkacky — Department Chemie - LMU München - Butenandtstr. 11 - 81377 München

During the last decade, different techniques of non-linear optical microscopy have become versatile tools for cell microscopy. The latest addition to this list is Coherent Anti-Stokes Raman Scattering (CARS) microsopy. Compared to other non-linear mircroscopies, CARS microscopy has the big advantage of offering chemical sensitivity, i.e. the presence of vibrational bands is monitored directly and no external labeling is necessary.

After the demonstration of three-dimensional CARS microscopy with a pulsed fs-laser system, recent years have seen many different technical developments. Most are aimed at improving the signal to background ratio by reducing and suppressing the non-resonant signal. We will demonstrate a new simple and straightforward approach, how this goal can be achieved. It will be shown how the bandwidth of broad-band fs-laser pulses can be spectrally focussed onto the vibrational resonance under investigation. For this purpose, the excitation pulses are chirped in order to keep their instantaneous frequency difference constant. Spectral features that are 100 times narrower than the excitation bandwidth are easily resolved. This approach is generaly applicable for other non-linear microscopical techniques. Its application to microscopy will be demonstrated with imaging of various biological samples.