Detecting forensic substances using commercially available SERS substrates and handheld Raman spectrometers.

Area of Science:

• Forensic Science
• Analytical Chemistry
• Materials Science

Background:

• Field detection of forensic substances is challenging, especially for pure or high-concentration samples.
• Handheld Raman spectroscopy is increasingly used but limited by sensitivity.
• Surface-enhanced Raman scattering (SERS) offers potential for enhanced sensitivity.

Purpose of the Study:

• To investigate the use of commercially available SERS substrates and handheld spectrometers for ultra-sensitive in-field detection of common forensic substances.
• To demonstrate the forensic generality and high performance of SERS for trace-level analysis.
• To interpret the SERS enhancement mechanisms using computational simulations.

Main Methods:

• Utilized commercially available silver nanopillar SERS substrates and handheld Raman spectrometers.
• Employed 3D Finite Element Method (FEM) simulations to understand SERS enhancement.
• Applied Density Functional Theory (DFT) simulations to interpret substance detection.
• Tested detection limits for Cyclosarin, RDX, Amphetamine, and Picric acid.

Main Results:

• Achieved ultra-sensitive detection of forensic substances down to femtogram levels.
• Demonstrated the capability of handheld SERS for trace-level forensic analysis.
• Validated the effectiveness of Ag nanopillar substrates for enhancing Raman signals.
• Confirmed the forensic applicability across multiple substance types.

Conclusions:

• Ultra-sensitive in-field SERS detection of key forensic substances is feasible with commercial equipment.
• This analytical method significantly enhances detection capabilities for first responders and forensic investigators.
• The combination of SERS substrates and handheld spectrometers offers a powerful tool for field evidence collection.