23-Mar-2020 - Friedrich-Schiller-Universität Jena

Unraveling the optical parameters: New method to optimize plasmon enhanced spectroscopy

For exploring the nanoscale far beyond the optical resolution limit, tip-enhanced Raman spectroscopy (TERS) is widely recognized as an essential yet still emergent technique. Using this marker-free spectroscopic method scientists gain insights into the structural and chemical composition of surfaces with nanoscale resolution, which are not accessible with other methods. Examples where such nanoscale resolution spectroscopies are crucial are structure investigations, of novel materials (e.g. diamond layers, 2D materials etc.), of protein aggregates, discussed as triggers for diseases like diabetes type II or Alzheimer's, or even of catalytical reactions at work. However, scientists' lack of comprehension of crucial parameters of the actual probe still limits the potential of TERS as a user-friendly analytical tool. Until now scientists have not been able to unravel the most fundamentally relevant experimental parameters as the tip's surface plasmon resonance, heating due to near-field temperature rise, and the link towards spatial resolution.

In a new paper in "Light: Science & Application", a research team from Jena, Germany now presents the first accessible method to gain unprecedented insights into the plasmonic activity of a single nanoparticle during a typical TERS experiment. Prof. Volker Deckert from the Leibniz Institute of Photonic Technology, Jena, and Dr. Marie Richard-Lacroix from the Friedrich Schiller University Jena propose a straightforward and purely experimental method to assess the plasmon resonance and near-field temperature experienced exclusively by the molecules directly contributing to the TERS signal. Using standard TERS experimental equipment, the scientists evaluate the detailed near-field optical response, both at the molecular level and as a function of time by probing simultaneously the Stokes and anti-Stokes spectral intensities. This enables them to characterize the optical properties of each individual TERS tip during the measurement.

"The proposed method could be a major step to improve the usability of TERS in day-to-day operation", Prof. Deckert explains. "The actual conditions to which the molecules are submitted from one experiment to the next can now be investigated and optimized directly, in real-time, and at the sample scale." This is especially relevant when it comes to examining biological samples like e.g. proteins which cannot tolerate high temperatures.

"To the best of our knowledge, no other accessible methodology opens up access to such a wealth of information on the plasmonic activity during a typical TERS experiment", Dr. Richard-Lacroix says.

"We believe that this methodology will contribute to improve the accuracy of theoretical models and facilitate any experimental plasmonic investigation and the application of TERS in the field of nanoscale thermometry", the scientists foresee.

Facts, background information, dossiers
  • plasmon resonance
More about Uni Jena
  • News

    A sharper look at the interior of semiconductors

    Images provide information – what we can observe with our own eyes enables us to understand. Constantly expanding the field of perception into dimensions that are initially hidden from the naked eye, drives science forward. Today, increasingly powerful microscopes let us see into the cells ... more

    How smart, ultrathin nanosheets go fishing for proteins

    An interdisciplinary team from Frankfurt and Jena has developed a kind of bait with which to fish protein complexes out of mixtures. Thanks to this “bait”, the desired protein is available much faster for further examination in the electron microscope. The research team has christened this ... more

    Controlling cells with light

    Photopharmacology investigates the use of light to switch the effect of drugs on and off. Now, for the first time, scientific teams from Jena, Munich, and New York have succeeded in using this method to control a component of cells that was previously considered inaccessible. Present everyw ... more

More about IPHT
  • News

    Detect neurodegenerative diseases such as Alzheimer's by a simple eye scan?

    Diagnosing Alzheimer's disease through a non-invasive eye scan long before symptoms appear: a European research team involving Leibniz IPHT has come one step closer to achieving this goal. Using a laser-based method, the researchers have succeeded in discriminating between healthy and Alzhe ... more

    A microscope for everyone

    Modern microscopes used for biological imaging are expensive, are located in specialized laboratories and require highly qualified staff. To research novel, creative approaches to address urgent scientific issues — for example in the fight against infectious diseases such as Covid-19 — is t ... more

    Synapses in 3D

    Our brain consists of countless nerve cells that transmit signals from one cell to the next. The connections between these cells, the synapses, provide a key to understanding how our memory works. An American research team in collaboration with Rainer Heintzmann from the Leibniz Institute o ... more