Infrared optical properties of phosphorus-derived smoke

Area of Science:

• Atmospheric Chemistry
• Aerosol Science
• Optical Physics

Background:

• Elemental phosphorus combustion generates visible white smoke.
• Understanding the composition and evolution of phosphorus smoke is crucial for atmospheric and safety applications.
• Previous studies lacked detailed characterization of smoke particle structure and optical properties.

Purpose of the Study:

• To characterize the chemical and physical properties of phosphorus-derived smoke particles.
• To investigate the influence of environmental conditions (relative humidity, time) on smoke extinction spectra.
• To develop a descriptive model for phosphorus smoke particle formation and evolution.

Main Methods:

• Measurement of infrared extinction spectra (7-14 microm) of phosphorus smoke under varying relative humidity.
• Application of Lorenz-Mie theory for spectral analysis.
• Time-resolved spectral measurements over 280 minutes.

Main Results:

• Phosphorus smoke particles are radially inhomogeneous layered spheres, not homogeneous o-phosphoric acid droplets.
• Smoke extinction is dependent on relative humidity.
• Spectra show smoke particles evolve towards o-phosphoric acid aerosol over time.
• Optical constants of smoke particles were determined as functions of humidity and time.

Conclusions:

• A novel model describing phosphorus smoke particles as quasi-stable, layered spheres is proposed.
• The study provides insights into the atmospheric transformation of phosphorus combustion products.
• The findings are relevant for predicting the behavior and impact of phosphorus smoke in different environments.