Nikitin, A. Y. https://orcid.org/0000-0002-2327-0164
Alonso-González, P.
Vélez, S.
Mastel, S.
Centeno, A.
Pesquera, A.
Zurutuza, A.
Casanova, F.
Hueso, L. E. https://orcid.org/0000-0002-7918-8047
Koppens, F. H. L.
Hillenbrand, R.
Article History
Received: 11 November 2015
Accepted: 16 February 2016
First Online: 21 March 2016
Competing interests
: R.H. is a co-founder of Neaspec GmbH, a company producing scattering-type scanning near-field optical microscope systems such as the one used in this study. All other authors declare no competing financial interests.