Photophoresis of irradiated spheres: absorption centers

The source function describing the distribution of the power dissipation inside irradiated spherical particles is evaluated and is shown to be sensitive to minor errors in evaluating the Ricatti–Bessel functions used in describing the electric field within the particle. Errors in the functions that lead to only 1 or 2% errors in the total rate of energy absorption completely distort the temperature distribution within a particle and the associated photophoretic force. Representative calculations of the source function are provided for size parameters in the range 0.5 < πD/λ < 20 for selected refractive indices (n = 1.5−5 for k = 0.2, k = 0.01−10 for n = 1.3−3.0).