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Competition Between Extinction and Enhancement in Surface Enhanced Raman Spectroscopy
Thomas van Dijk1, Sean T Sivapalan, Brent M Devetter
1Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA, Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA, Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA, and Department of Mechanical Science and Engineering, Chemical and Biomolecular Engineering and University of Illinois Cancer Center, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA.
Metallic nanoparticles offer ultrasensitive sensing via surface-enhanced Raman scattering (SERS). This study reveals that signal enhancement and light extinction are linked, impacting SERS sensitivity in complex samples.
Area of Science:
- Nanotechnology
- Spectroscopy
- Materials Science
Background:
- Conjugated metallic nanoparticles are key for ultrasensitive, multiplexed sensing in 3D biological samples using surface-enhanced Raman scattering (SERS).
- Understanding nanoparticle interactions is crucial for optimizing SERS performance.
Purpose of the Study:
- To investigate the relationship between signal enhancement and light extinction in metallic nanoparticle collections.
- To explain counterintuitive SERS signal behavior observed at different excitation wavelengths and nanoparticle concentrations.
Main Methods:
- Development of an effective medium theory to model nanoparticle behavior.
- Analysis of excitation wavelength, particle enhancement factor, and concentration effects on SERS signals.
Main Results:
- Signal enhancement and extinction are intrinsically linked and compete within nanoparticle collections.
- Raman signal diminishes upon excitation at plasmon resonance.
- Increased nanoparticle concentration at off-resonance excitation can paradoxically decrease signal intensity.
Conclusions:
- The developed theory explains the observed phenomena, highlighting the dual role of nanoparticles in enhancing local fields and attenuating light.
- Optimal SERS performance requires careful selection of excitation wavelength, particle properties, and concentration.
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