Particle size distribution measurement in a flowing aerosol using dynamic light scattering

Simulated and experimental data were used to investigate the particle size distribution (PSD) recovery from a flowing aerosol via dynamic light scattering (DLS). It is found that, for a unimodal PSD, increasing the flow velocity leads to an increase in the error of the peak position, a decrease in the peak height and a broadening of the PSD. This is exacerbated for larger aerosol particles. For a bimodal PSD, the separation of the two peaks decreases and results in a single-peak PSD as the velocity increases. The effect of velocity on the measurement is similar to adding signal noise, which increases with the velocity. This effect is related to the measured aerosol particle size. The larger the particles, the lower the signal-to-noise ratio. By comparing DLS measurement results for flowing and non-flowing aerosol samples, it is possible to determine the maximum flow rate at which measurements can be usefully made.

Automated summary

The study shows that increasing flow velocity affects the recovery of particle size distribution via dynamic light scattering, particularly for unimodal and bimodal PSDs. Increasing velocity can lead to errors in peak position and broadening of PSD for unimodal PSD, and can result in a single-peak PSD for bimodal PSD. There is a correlation between velocity and signal noise in measurements, with larger particles having lower signal-to-noise ratio.