Visualisation of plasmonic fields at the nanoscale with single molecule localisation microscopy Christian Steuwe a,b , Miklos Erdelyi a , G. Szekeres c , M. Csete c , Jeremy J Baumberg b , Sumeet Mahajan* d and Clemens F. Kaminski* a a Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge, CB2 3RA, UK b Nanophotonics Centre, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK c Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9, Hungary d Institute for Life Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, UK Corresponding authors: SM (s.mahajan@soton.ac.uk), CFK(cfk23@cam.ac.uk) Plasmonic coupling of light to free electrons on metallic surfaces allows the confinement of electric fields far below the optical diffraction limit. Scattering processes of molecules placed into these plasmonic ‘hotspots’ are dramatically enhanced [1] which is commonly used to increase the sensitivity of spectroscopic techniques for biological and chemical sensor applications [2, 3] . Strikingly, hardly any measurement technique exists for the direct visualisation and characterisation of the underlying nanoscopic electromagnetic field distributions that either do not perturb the field [3, 4] or require complex electron beam imaging [5] . In this paper we introduce surface enhanced localisation microscopy (SELM), demonstrating the direct visualisation of fields on patterned plasmonic substrates using optical super resolution microscopy [6] . The observed strong photo-blinking behaviour of single molecules in plasmonic fields is exploited in SELM to map electromagnetic field distributions at nanometer resolutions. Engineered nanostructured surfaces, which can sustain plasmon modes, are extremely important in technological applications such as enhancement of Raman scattering for detection of single molecules [7] or to obtain reproducible characteristics for quantitative diagnostics [8] . The morphological characterisation of such nanostructures is generally obtained using scanning electron microscopy techniques [9] . Recently, using surface-attached photoactivatable fluorescent proteins morphological optical imaging of metallic nanostructures has also been shown to be possible [10] . Nonetheless, only a few techniques allow measuring electromagnetic field distributions of plasmonic modes with nanometer resolution [5, 11] without distortion and special or complex requirements such as photoactivable molecules. Therefore, finite and boundary element simulations are widely used to predict the field distribution on plasmonic surfaces, but this comes with significant uncertainties and limitations. Simulation results are algorithm dependent and can only predict fields for ‘perfect’ structures. In practice, however, structures free of imperfections do not exist [12] . We demonstrate our technique to map nanoscopic EM field patterns in exemplar plasmonic structures, such as: Nanovoids, ‘dish-like’ structures with variable diameter D [13] (Figure 1A) and Klarite®, featuring a pyramidal pit structure as shown in Figure 1B. SEM images of both structures are shown in Figure 2A and B. Afterwards we compare experimental results with data obtained from Nanoimaging and Nanospectroscopy III, edited by Prabhat Verma, Alexander Egner, Proc. of SPIE Vol. 9554, 95540Q · © 2015 SPIE · CCC code: 0277-786X/15/$18 · doi: 10.1117/12.2190835 Proc. of SPIE Vol. 9554 95540Q-1 DownloadedFrom:http://proceedings.spiedigitallibrary.org/on09/03/2015TermsofUse:http://spiedigitallibrary.org/ss/TermsOfUse.aspx