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Associate Professor of Chemistry
Adjunct Associate Professor of Physics
Ph.D. Physics,
Max-Planck-Institute for Quantum Optics and Technische
Universität Munich, 1999
(Physical Chemistry, Nanooptics)
(206) 543-2906
Email: raschke@chem.washington.edu
Raschke group website
The research in our group is centered around the linear and nonlinear optical spectroscopy of surfaces and on the nanoscale. We explore the optical antenna properties of metallic nanostructures to spectrally and spatially tailor optical fields.In combination with scanning probe methods (AFM, STM) this provides new routes for optical near-field imaging with ultrahigh spatial resolution far beyond the diffraction limit. We apply these techniques for the investigation of polymer and biomolecular nanostructures, surface photochemistry, molecular plasmonics, and single molecule spectroscopy as well as for probing surface electron dynamics and surface electron-phonon interaction.
We study the properties of plasmonic metal nanostructures to transfer and concentrate light to highly confined regions. The spectral selectivity of the confinement sensitively depends on sample material and geometric details. The fundamental understanding of the near-field coupling between the radiation field and optical excitation of the medium thus provides the basis for the rational design of photonic devices for bioanalytic sensor applications, wave guides, optical switches, or nanoscopic light sources.
Taking advantage of the optical antenna properties of a nanoscopic metal tip allows for a new combination of optical spectroscopy with scanning probe techniques (scattering-type near-field microscopy). Here, our group has achieved scanning probe vibrational Raman microscopy with single molecule sensitivity. We have also advanced infrared microscopy for chemical analysis obtaining ultrahigh spatial resolution down to 10 nm. Applicable under ambient and in situ conditions this allows us to probe microscopic composition, thermodynamics phases, or chemical functionality of nanoscale materials that have been difficult to access so far.
The nonlinear optics on the nanoscale is a yet largely- unexplored
research area. Taking advantage of the higher symmetry selectivity of
the nonlinear response compared to linear optics allows for the unique
distinction of surface and bulk properties for certain nanostructures.
Here, we study ferroelectric ordering, electron-vibration coupling and
its ultrafast dynamics of intrinsic and adsorbate covered planar
surfaces as well as of nanostructures using both far-field techniques
and scanning probe near-field microscopies.
"Scanning probe Raman spectroscopy with single molecule sensitivity." C. C. Neacsu, J. Dreyer, N. Behr, and M. B. Raschke, Phys. Rev. B. 73, 193406 (2006).
"Electron dynamics of silicon surface states: Second-harmonic hole burning on Si(111)7x7." J. A. McGuire, M. B. Raschke, and Y. R. Shen, Phys. Rev. Lett. 96, 087401 (2006).
"Apertureless near-field vibrational imaging of block-copolymer nanostructures with ultrahigh spatial resolution." M. B. Raschke et al., ChemPhysChem 6, 2197 (2005).
"Second-harmonic generation from nanoscopic metal tips: Generalized symmetry selection rules from single nanostructures." C. C. Neacsu, G. A. Reider, and M. B. Raschke, Phys. Rrev. B 71, 201402(R) (2005).
"Doubly-resonant sum-frequency generation for surface studies." M. B. Raschke, M. Hayashi, S. H. Lin, and Y. R. Shen, Chem. Phys. Lett. 359, 367 (2002).
Feodor Lynen Fellowship of the Alexander von Humboldt Foundation
Otto-Hahn-Medal of the Max-Planck Society
Fulbright Fellowship
Friedrich Naumann Foundation Scholarship