Practical control of SERRS enhancement.

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Nanotechnology

Background:

• Surface-enhanced resonance Raman scattering (SERRS) offers quantitative and sensitive chemical analysis.
• Controlling silver colloid aggregation is crucial for optimizing SERRS performance.
• Previous studies focused on analyte chemisorption and specialized dyes for SERRS.

Purpose of the Study:

• To investigate the use of poly-L-lysine as an organic aggregating agent for controlled silver colloid aggregation in SERRS.
• To study the relationship between excitation frequency, plasmon resonance, and molecular chromophore absorbance.
• To compare enhancement profiles with and without aggregating agents.

Main Methods:

• Controlled addition of poly-L-lysine to silver colloid to modify zeta potential and induce aggregation.
• Analysis of excitation frequency, surface plasmon resonance, and molecular chromophore absorbance.
• Comparison of SERRS enhancement using sodium chloride as an aggregating agent.

Main Results:

• Poly-L-lysine allows for controlled aggregation, reducing zeta potential.
• Without aggregation, SERRS enhancement strongly depends on molecular chromophore and plasmon resonance frequencies.
• Aggregation with sodium chloride yields higher enhancement and a broader profile, less dependent on chromophore frequency.

Conclusions:

• Controlled aggregation using agents like poly-L-lysine is key to enhancing SERRS sensitivity.
• Aggregation-induced enhancement mechanisms become dominant, reducing chromophore-specific frequency dependence.
• SERRS achieves greater enhancement than SERS, highlighting the continued importance of the chromophore.