infrared spectroscopy with nanostructures



      machine for FTIR spectroscopy

    Traditional far-field infrared microscopy

    In the group of Prof. Thomas Taubner, also traditional far-field infrared microscopy is applied to investigate resonant nanostructures for infrared light: metallic nanostructures can act as antennas for infrared light and (similar to a probe tip for SNOM) lead to locally enhanced electromagnetic fields. These field enhancements can be used for surface enhanced infrared absorption (SEIRA) in order to detect thin molecular layers. In the course of two bachelor and one diploma thesis we conducted nanosphere lithography, which uses self-organizing nanospheres, in order to fabricate nanostructures and demonstrate enhanced infrared absorption of molecules adsorbed to them. For a more intensified study on this topic and thus for the further increase of sensitivity compared to conventional IR-spectroscopy, Tao Wang, a new postdoctoral researcher is employed in 9/2012. By using coupled systems, optimized detection techniques and the application of tunable lasers, improvements in terms of sensitivity are achieved. For the future, we also plan to investigate SEIRA in liquids and combine it with microfluidics for the specific detection of clinically relevant substances.

    "Optical properties of single infrared resonant circular microcavities for Surface Phonon Polaritons“
    T. Wang, P. Li, B. Hauer, D.N. Chigrin and T. Taubner.
    Nano Letters, Articles ASAP, DOI: 10.1021/nl4020342

    “Mapping infrared antenna resonances of particle arrays fabricated by colloidal lithography”
    J.M. Hoffmann, X. Yin, T.W.W. Mass, J. Richter, A. Hartung and T. Taubner.
    Journal of physical Chemistry C, 117, 11311-11316 (2013).

    “Surface enhanced infrared spectroscopy with gold strip gratings”
    T. Wang, V.H. Hguyen, A. Buchenauer, U. Schnakenberg and T. Taubner.
    Optics Express, 21, 9005-9010 (2013).

      diagramm to show phase-change nanooptics phase-change nanooptics

    Usage of "phase-change material"

    Another topic which can be addressed by farfield infrared microscopy, is the application of so-called phase-change materials, which are fundamentally investigated by the group of Prof. Matthias Wuttig, for tuning the resonance position of infrared nanoantennas. First promising results were shown in the master's thesis of our student Kathrin Schönauer, advised by Prof. Taubner and Prof. Wuttig, in which, regarding resonance tuning, much better numbers were presented than what has been shown in literature until then. Since 10/2011, this topic is continued by our former PhD student Ann-Katrin Michel, who works with well-defined nanoantennas fabricated by electron beam lithography in the cleanroom of the Institute of Physics II. The goal of these projects is to fabricate infrared optical devices, which can be tuned electrically as well as optically. In the future this could lead to individually programmable metamaterials.

    “Using low-loss phase-change materials for mid-infrared antenna resonance switching”.
    A.-K. U. Michel, D. Chigrin, T.W.W. Mass, K. Schönauer, M. Salinga, M. Wuttig and T. Taubner.
    Nano Letters, 13, 3470-3475 (2013).