Berlin 2001 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 9: New Methods

CPP 9.2: Vortrag

Mittwoch, 4. April 2001, 16:05–16:25, 112

Coherent Anti-Stokes Raman Scattering (CARS) Microscopy: Vibrational Imaging and Spectroscopy with High Sensitivity — •A. Volkmer, J.-X. Cheng, L.D. Book, and X.S. Xie — Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA

We demonstrate theoretically and experimentally an unconventional phase matching condition for coherent anti-Stokes Raman scattering (CARS) microscopy, which allows vibrational imaging and spectroscopy of biological systems with high sensitivity, noninvasiveness, and three-dimensional sectioning capability [1].

We have made significant new advances in this novel multi-photon microscopy technique with respect to the detection sensitivity, which was limited by the presence of solvent and/or non-resonant signal. Calculations show that epi-detected CARS (E-CARS) signals are present for scatterers smaller than the wavelength of light, whereas the large background signals from the surrounding solvent are suppressed by destructive interference. Using this novel approach, we demonstrate CARS decay kinetics on the femtosecond time scale and CARS spectra of sub-micron sized samples. Application of E-CARS microspectroscopy to cellular studies in the biologically relevant amide band fingerprint region (1000-1700 cm-1) will be presented. Small intra-cellular features have been identified on the basis of their vibrational contrast, and thus require no natural or artificial fluorophores that are prone to photobleaching.

[1] A. Zumbusch, G.R. Holtom, and X.S. Xie, Phys. Rev. Lett., 82, 4142 (1999).