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Nanooptics is concerned with the interaction between nanometer-sized objects and confined or locally enhanced electromagnetic light fields. Optical antennas which can scan individual nanostructures establish a novel access to the nanoworld. We employ a home-built scanning tunneling microscope (STM) at cryogenic temperature which allows detecting light emission from its scanning metallic tip. The sharp tunnel current of the STM can very selectively excited luminescence from individual quantum systems like organic molecules, quantum dots, and quantum wires which have previously been imaged and characterized by tunneling spectroscopy. The spectral analysis of the emitted light allows investigating inelastic electron transitions and can even access excited states without net charge (neutral electron-hole pairs). Moreover, fast optical detectors provide a straight-forward means to follow processes on the atomic scale with high temporal resolution. They even allow the observation of photon correlations from molecular single photon emitters with nanometer precision by employing Hanbury Brown-Twiss interferometry in the STM. Recently, we were surprised to find even photon-pair emission from pure metallic tunnel junctions which raises question on the underlying electron-plasmon coupling mechanism. The detection of locally induced electroluminescence provides a powerful and fascinating extension of scanning tunneling microscopy.


Responsible Scientist

Dr. Klaus Kuhnke


Team Members

Abhishek Grewal, Klaus Kuhnke, Christopher Leon, Anna Roslawska


Review on the Research Field

Klaus Kuhnke, Christoph Große, Pablo Merino, and Klaus Kern
Atomic-Scale Imaging and Spectroscopy of Elecroluminescence at Molecular Interfaces 
Chem. Rev. 117 (2017) pp. 5174-5222

Key Publications

C. Leon, A. Rosławska, A. Grewal, O. Gunnarsson, K. Kuhnke, and K. Kern
Photon super-bunching from a generic tunnel junction
arXiv 1805.10234, (2018)

A. Rosławska, P. Merino, C. Große, C.C. Leon,  O. Gunnarsson, M. Etzkorn, K. Kuhnke, K. Kern
Single charge and exciton dynamics probed by molecular-scale-induced electroluminescence
NanoLetters 18, pp 4001-4007, (2018)

P. Merino, A. Rosławska, C. Große, C.C. Leon, K. Kuhnke, K. Kern
Bimodal Exciton-Plasmon Light Sources Controlled by Local Charge Carrier Injection
Sci. Adv. 4, eaap8349  (2018)

K. Kuhnke, V. Turkowski, A. Kabakchiev, T. Lutz, T.S. Rahman, and K. Kern
Pentacene excitons in strong electric fields
ChemPhysChem 19, 277 (2018)

C. Große, P. Merino, A. Rosławska, O. Gunnarsson, K. Kuhnke, and K. Kern
Submolecular Electroluminescence Mapping of Organic Semiconductors
ACS Nano 11, pp 1230-1237, (2017)

C. Große, O. Gunnarsson, P. Merino, K. Kuhnke, and K. Kern
Nanoscale Imaging of Charge Carrier and Exciton Trapping at Structural Defects in Organic Semiconductors 
Nano Lett. 16 (3), pp 2084–2089 (2016)

P. Merino, C. Große, A. Roslawska, K. Kuhnke, and K. Kern
Exciton dynamics of C60-based single photon emitters by Hanbury Brown-Twiss Scanning Tunneling Microscopy
Nature Commun. 6:8461 (2015)

C. Große, A. Kabakchiev, T. Lutz, R. Froidevaux, F. Schramm, M. Ruben, M. Etzkorn, U. Schlickum, K. Kuhnke, and K. Kern
Dynamic Control of Plasmon Generation by an Individual Quantum System
Nano Lett. 14, 5693 (2014)

C. Große, M. Etzkorn, K. Kuhnke, S. Loth, and K. Kern
Quantitative mapping of fast voltage pulses in tunnel junctions by plasmonic luminescence
Appl. Phys. Lett. 103, 183108 (2013)

T.Lutz, C.Große, C.Dette, A.Kabakchiev, F.Schramm, M.Ruben, R.Gutzler, K.Kuhnke, U.Schlickum, and K.Kern

Molecular orbital gates for plasmon excitation
Nano Letters 13, 2846 (2013)
T.Lutz, A.Kabakchiev, T.Dufaux, C.Wolpert, Z.Wang, M.Burghard, K.Kuhnke, and K.Kern

Scanning tunneling luminescence of individual CdSe nanowires
Small 7, 2396(2011)

A.Kabakchiev, K,Kuhnke, T.Lutz, and K. Kern
Electroluminescence from individual pentacene nanocrystals
Chem Phys Chem 11, 3412 (2010)

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