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Local field enhancement of an infinite conical metal tip illuminated by a focused beam
Author(s) -
Zhang Weihua,
Cui Xudong,
Martin Olivier J. F.
Publication year - 2009
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.2439
Subject(s) - conical surface , optics , raman spectroscopy , ligand cone angle , apex (geometry) , materials science , field (mathematics) , plane (geometry) , focus (optics) , cardinal point , physics , geometry , mathematics , pure mathematics , composite material
We present a systematic numerical investigation of conical metal tips which are commonly used in tip‐enhanced Raman spectroscopy (TERS). Different from previous studies, we focus on how the tip length and the illumination condition influence the local field enhancement at the tip apex, and provide a useful reference for real experiments. In particular, we show that the type of illumination has a dramatic influence on the field enhancement: a localized illumination spot—as used in experiments—producing a very different response than a plane wave illumination—as usually used in previous models. Also, the effect of the different geometrical parameters, such as the sharpness of the tip apex and the cone angle, provides guidance to optimize the tip design. Finally, we investigate the influence of the substrate and compare numerical data with results deduced from a simplified model, finding good agreement. This brings new insights into the enhancement mechanism of TERS. Copyright © 2009 John Wiley & Sons, Ltd.