Dual-Scattering Near-Field Microscope for Correlative Nanoimaging of SERS and Electromagnetic Hotspots.
Surface-enhanced Raman spectroscopy (SERS) enables sensitive chemical studies and materials identification, relying on electromagnetic (EM) and chemical-enhancement mechanisms. Here we introduce a tool for the correlative nanoimaging of EM and SERS hotspots, areas of strongly enhanced EM fields and Raman scattering, respectively. To that end, we implemented a grating spectrometer into a scattering-type scanning near-field optical microscope (s-SNOM) for mapping of both the elastically and inelastically (Raman) scattered light from the near-field probe, that is, a sharp silicon tip. With plasmon-resonant gold dimers (canonical SERS substrates) we demonstrate with nanoscale spatial resolution that the enhanced Raman scattering from the tip is strongly correlated with its enhanced elastic scattering, the latter providing access to the EM-field enhancement at the illumination frequency. Our technique has wide application potential in the correlative nanoimaging of local-field enhancement and SERS efficiency as well as in the investigation and quality control of novel SERS substrates.
Freie Universität Berlin , 14195 Berlin, Germany.|CIC nanoGUNE , 20018 Donostia-San Sebastián, Spain.
Patryk
0000-0001-9180-786X
P
Kusch
CIC nanoGUNE , 20018 Donostia-San Sebastián, Spain.
Stefan
S
Mastel
Freie Universität Berlin , 14195 Berlin, Germany.
Niclas S
NS
Mueller
CIC nanoGUNE , 20018 Donostia-San Sebastián, Spain.
Nieves
N
Morquillas Azpiazu
Photonics Laboratory, ETH Zürich , 8093 Zürich, Switzerland.
Sebastian
0000-0002-6485-3083
S
Heeg
National Graphene Institute, The University of Manchester , Manchester M13 9PL, United Kingdom.
Roman
R
Gorbachev
National Graphene Institute, The University of Manchester , Manchester M13 9PL, United Kingdom.
Fredrik
F
Schedin
Leibniz Institute of Photonic Technology , 07745 Jena, Germany.
Uwe
U
Hübner
CIC nanoGUNE , 20018 Donostia-San Sebastián, Spain.|IKERBASQUE, Basque Foundation for Science , 48013 Bilbao, Spain.
Jose I
JI
Pascual
Freie Universität Berlin , 14195 Berlin, Germany.
Stephanie
S
Reich
IKERBASQUE, Basque Foundation for Science , 48013 Bilbao, Spain.|CIC nanoGUNE and UPV/EHU , 20018 Donostia-San Sebastián, Spain.
Rainer
R
Hillenbrand
Raman scattering; SERS; hotspot mapping; plasmon; s-SNOM