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Observation and Analysis of Blinking Surface-enhanced Raman Scattering
Published on: January 11, 2018
Slow fluctuations in enhanced Raman scattering and surface roughness relaxation
D B Lukatsky1, G Haran, S A Safran
1Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel. lukatsky@amolf.nl
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|October 26, 2005
Summary
Surface-enhanced Raman scattering (SERS) fluctuations in single molecules are explained by dynamic nanometer-scale surface roughness relaxation. Laser power accelerates smoothing, while salt addition retards it, aligning with experimental observations.
Area of Science:
- Physical Chemistry
- Surface Science
- Spectroscopy
Background:
- Single-molecule surface-enhanced Raman scattering (SERS) exhibits slow fluctuations and "blinking."
- The underlying mechanisms for these spectral dynamics are not fully understood.
- Nanometer-scale surface roughness of plasmonic nanoparticles is a potential factor.
Purpose of the Study:
- To propose and theoretically investigate a model explaining SERS fluctuations based on dynamic surface roughness relaxation.
- To determine the influence of external factors like laser power and salt concentration on these dynamics.
Main Methods:
- Development of a theoretical model for surface roughness relaxation kinetics.
- Inclusion of effects from charges and optical electric fields.
- Analysis of two distinct classes of surface roughness with different dynamics.
Main Results:
- Fluctuations are attributed to the dynamic relaxation of nanometer-scale surface roughness.
- Two classes of roughness with distinct dynamics were identified, agreeing with experimental measurements.
- Theoretical predictions show laser power linearly accelerates surface smoothing, while salt addition retards it.
Conclusions:
- Dynamic relaxation of nanometer-scale surface roughness provides a viable explanation for SERS spectral fluctuations.
- Optical fields and salt concentration can modulate the kinetics of surface relaxation and thus the observed SERS fluctuations.
- The model offers a framework for understanding and potentially controlling SERS signal stability.
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