Detection and quantification of water-based aerosols using active open-path FTIR

Area of Science:

• Atmospheric chemistry and physics
• Spectroscopic analysis of aerosols

Background:

• Aerosols significantly impact ecosystems and require accurate property assessment.
• Understanding aerosol composition is crucial for diverse scientific and industrial applications.

Purpose of the Study:

• To investigate the efficacy of active Open-Path Fourier Transform Infra-Red (OP-FTIR) spectroscopy for quantifying atmospheric water droplets and solutes.
• To assess the performance of OP-FTIR in controlled aerosol environments with varying compositions.

Main Methods:

• Utilized a 20m spray tunnel to generate controlled hydrosol clouds.
• Employed OP-FTIR spectroscopy to measure water droplets with and without solutes (ammonium sulfate and ethylene glycol).
• Analyzed spectral data to establish relationships between extinction signals and solute concentrations.

Main Results:

• Demonstrated a linear correlation between spectral baseline shift and water load (R²=0.984).
• Established a linear relationship between integrated extinction and ammonium sulfate load (R²=0.972).
• Developed two methods for ethylene glycol quantification, achieving determination errors of 8% and 57%.

Conclusions:

• OP-FTIR spectroscopy is a viable tool for detecting water-based aerosol clouds.
• The study confirms OP-FTIR's potential for quantifying water droplets and specific solutes at low atmospheric concentrations.