Photophoresis of spherical particles in slip-flow regime

Abstract

Photophoresis is a particle-light-induced phenomenon with several applications, such as spectroscopy, three-dimensional displays, and nanomanufacturing, to name a few. This work synthesizes, criticizes, and compares the main hydrodynamic and gas-kinetic models developed to quantify photophoretic forces in the slip-flow regime for uniform light beams, contrasting their predictions with experimental data available in the literature. The results comparing the different models evidence the simplicity and accuracy of Loesche and Husmann's model, which is then confronted with the experimental data available in the literature. However, considering the noticeable effect of high irradiance levels on photophoretic forces, namely, when temperature variations significantly change the thermofluid properties of the gaseous layer around the particle, more experiments are recommended to validate theoretical models. Finally, considering the photophoretic models that depend on two asymmetry factors, J0 and J1, a physical interpretation of their meaning is provided, especially for the oscillations in the latter argued as the result of Mie resonance effects.