We report on tip enhanced Raman spectroscopy of GaAs(100) crystals taking advantage of the fields polarization to maximize the near-field contrast. Excitation parallel to either the [100] or the [110] crystallographic axis provide minimum far-field background provided that cross-or parallel-component of the Raman field are detected. Experiments highlight a tip-induced selective enhancement of the one-phonon longitudinal optical mode with respect to the transverse optical mode. We interpret this effect in terms of depolarization of the excitation field and beam deflection which breaks the polarization-based selection rules of the Raman scattering.
Different longitudinal optical - transverse optical mode amplification in tip enhanced Raman spectroscopy of GaAs(001)
Gucciardi P G;
2010
Abstract
We report on tip enhanced Raman spectroscopy of GaAs(100) crystals taking advantage of the fields polarization to maximize the near-field contrast. Excitation parallel to either the [100] or the [110] crystallographic axis provide minimum far-field background provided that cross-or parallel-component of the Raman field are detected. Experiments highlight a tip-induced selective enhancement of the one-phonon longitudinal optical mode with respect to the transverse optical mode. We interpret this effect in terms of depolarization of the excitation field and beam deflection which breaks the polarization-based selection rules of the Raman scattering.| File | Dimensione | Formato | |
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