Direct Measurement of Photoacoustic Signal Sensitivity to Aerosol Particle Size

Johannes W. Cremer, Paul A. Covert, Evelyne A. Parmentier, and Ruth Signorell

Continuing efforts to quantify the influence of aerosol light absorption upon global heat budgets rely on high-quality measurements of aerosol optical properties. Of the available methods, photoacoustic spectroscopy stands out as a sensitive method for measurements of aerosol absorption with minimal sample modification. Theoretical treatments of photoacoustic aerosol detection have predicted size-dependent damping of the photoacoustic signal as a result of particle thermal inertia. We provide experimental confirmation of this prediction using a single-particle photoacoustic spectrometer, which allows us to measure photoacoustic signals with high sensitivity and size-specificity. Both the magnitude and phase of the photoacoustic response follow the linearized description of the heat flux. The quantification of this effect provides a basis for future, system-specific case studies.

DOI