Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 64: Plasmonics and nanooptics III
O 64.6: Talk
Thursday, March 29, 2012, 11:45–12:00, MA 005
Near-field infrared microscopy with a broadband light source — •Stefanie Bensmann1, Christoph Janzen1, Reinhard Noll1, and Thomas Taubner1,2 — 1Fraunhofer-Institut für Lasertechnik (ILT), Aachen — 21. Physikalisches Institut 1A, RWTH Aachen
Scattering-type near-field infrared microscopy (s-SNOM) allows to record IR spectra at a wavelength-independent spatial resolution of approx. 30 nm. In general these spectra are taken sequentially by repeating a measurement at different wavelengths which can be time-consuming. Furthermore, conventional MIR laser sources have a limited spectral range excluding the possibility to examine samples like e.g. certain semiconductors, polar crystals and different polymers.
These problems can be circumvented by using broadband IR light sources covering an extended frequency range. They allow to record a full spectrum within a single measurement (interferogram with Fourier transformation) [1-3]. However, thermal sources or a laser power of less than 1 mW only permit the study of samples with a strong resonance. We present first spectra recorded with a broadband IR laser with a power of several milliwatt at 8.9-13.7 μm that is currently developed at the ILT with the NeaSNOM (near-field optical microscope from Neaspec, www2.neaspec.com). This new system will extend the spectral range covered and allow to examine samples with weaker resonances.
[1] M. Brehm et al., Optics Express 15, p. 11222, 2006.
[2] S. Amarie et al., Optics Express 17, p. 21794, 2009.
[3] F. Huth et al., Nature Materials 10, p. 352, 2011.