Tip-enhanced Raman scattering: Influence of the tip-surface geometry on optical resonance and enhancement

Bruno Pettinger (1) , Katrin F. Domke (2) , Dai Zhang (3) , Gennaro Picardi (4) , Rolf Schuster (5)

1 Physikalische Chemie
2 Biosurface Spectroscopy
3 Institut für Physikalische und Theoretische Chemie
4 LPICM - Laboratoire de physique des interfaces et des couches minces [Palaiseau]
5 Institut für Physikalische Chemie [Karlsruhe]

The tip-sample distance (z) dependence of tip-enhanced Raman scattering (TERS) has been investigated. The intensities of both, the Raman lines and the broad TERS background, exhibit strong decays with increasing z, which are nearly complete within 10 nm withdrawal of the STM tip in z direction. Interestingly, the maximum of the broad Lorentzian-shaped TER background is substantially blue shifted in energy with z. This effect is ascribed to a corresponding blue shift of the energies of localized plasmon modes upon tip retraction. Both experimental results fit very well data of a simple theoretical near-field model.

Keywords: Tip-enhanced Raman spectroscopy; Influence of the tip-surface geometry on optical resonance and enhancement; Scanning tunneling microscopy; Vibrations of adsorbed molécules; Single crystal surfaces

Domains: Physics [physics]; Physics [physics]; Chemical Physics [physics.chem-ph]

Bruno Pettinger, Katrin F. Domke, Dai Zhang, Gennaro Picardi, Rolf Schuster. Tip-enhanced Raman scattering: Influence of the tip-surface geometry on optical resonance and enhancement. Surface Science, 2009, 603, pp.1335-1341. ⟨hal-00838021⟩