title: Light depolarization induced by metallic tips in apertureless near-field optical microscopy and tip-enhanced Raman spectroscopy.
abstract: We have investigated the depolarization effects of light scattered by sharp tips used for apertureless near-field optical microscopy. Dielectric and metal coated tips have been investigated and depolarization factors between 5 and 30% have been measured, changing as a function of the incident light polarization and of the tip shape. The experimental results are in good agreement with theoretical calculations performed by the finite element method, giving a near-field depolarization factor close to 10%. The effect of depolarization has been investigated in polarized tip-enhanced Raman spectroscopy (TERS) experiments; the depolarization gives rise to forbidden Raman modes in Si crystals.
authors: CNR-Istituto per i Processi Chimico-Fisici, sezione Messina, Salita Sperone, Contrada Papardo, I-98158 Faro Superiore, Messina, Italy.
authors: P G
authors: PG
authors: Gucciardi
authors: M
authors: M
authors: Lopes
authors: R
authors: R
authors: Déturche
authors: C
authors: C
authors: Julien
authors: D
authors: D
authors: Barchiesi
authors: M
authors: M
authors: Lamy de la Chapelle