title: Optical near-field excitation at commercial scanning probe microscopy tips: a theoretical and experimental investigation.
abstract: A systematic study of the influence of the excitation angle, the light polarization and the coating thickness of commercial SPM tips on the field enhancement in an apertureless scanning near-field optical microscope is presented. A new method to optimize the alignment of the electric field vector along the major tip axis by measuring the resonance frequency was developed. The simulations were performed with a MNPBEM toolbox based on the Boundary Element Method (BEM). The influence of the coating thickness was investigated for the first time. Coatings below 40 nm showed a drastic influence both on the resonance wavelength and the enhancement. A shift to higher angles of incidence for the maximum enhancement could be observed for greater tip radii.
authors.affiliation: Department of Physical Chemistry, University of Vienna, Währinger Strasse 42, A-1090 Vienna, Austria. wolfgang.kautek@univie.ac.at.
authors.forename: Christoph
authors.initials: C
authors.lastname: Huber
authors.forename: Andreas
authors.initials: A
authors.lastname: Trügler
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hohenester
authors.forename: Yehiam
authors.initials: Y
authors.lastname: Prior
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kautek