Constructing a Raman and surface-enhanced Raman scattering spectral reference library for fine-particle analysis.

Area of Science:

• Environmental Science
• Analytical Chemistry
• Spectroscopy

Background:

• Haze pollution from fine particles poses significant health risks, particularly in China.
• Raman and surface-enhanced Raman scattering (SERS) are valuable for analyzing fine particle composition.
• A comprehensive Raman spectral library for fine particles is currently lacking.

Purpose of the Study:

• To develop a comprehensive reference library of Raman and SERS spectra for common fine particle components.
• To address limitations in SERS analysis caused by substrate and excitation wavelength variability.
• To facilitate accurate identification of fine particle constituents for pollution studies.

Main Methods:

• Conducted SERS experiments using a portable Raman spectrometer with silver (Ag) foil and gold nanoparticles (Au NPs) substrates and a 785 nm laser.
• Analyzed three main particle types: sulfate-nitrate-ammonium (SNA), organic material, and soot, encompassing 39 chemical substances.
• Recorded solid Raman, liquid Raman, and SERS spectra, creating a library of 105 spectra.

Main Results:

• Established a fine-particle reference library with 105 spectra for 39 substances.
• Observed that solid-liquid phase transitions primarily caused spectral differences for soot and SNA.
• Noted minimal substrate effect from Ag foil, while Au NPs induced a significant red shift in polycyclic aromatic hydrocarbon peaks.

Conclusions:

• The constructed spectral library enables rapid and accurate identification of fine particle substances.
• Distinct characteristic peaks across solid Raman, liquid Raman, and SERS spectra aid in substance differentiation.
• This resource is expected to advance the identification of fine particles in air pollution research.