Vl. Kononenko et Yk. Shimkus, PHOTOPHORESIS OF LARGE ABSORBING PARTICLES IN A TRANSPARENT LIQUID, Colloid journal of the Russian Academy of Sciences, 59(5), 1997, pp. 609-619
A theory of solid absorbing particle photophoresis for the case rho =
2 pi a/lambda much greater than 1, where a is the particle radius and
lambda is the wavelength of light, was designed. Using the geometrical
optics approximation, the light intensity distribution inside the par
ticle, which depends on rho and the optical parameters of a particle,
was obtained. On this basis, the characteristic temperature distributi
ons, which are caused by the light absorption inside the particle, wer
e calculated. Photophoretic mobility (PPM) of a particle surrounded by
an electrolyte solution was calculated based on the solution of the N
avier-Stokes equation for a thin subsurface layer of a liquid with the
Boltzmann ion concentration distribution in the field of the particle
surface potential. Numerical calculations were made; a general analys
is of the optical and thermal fields was carried out; and an analysis
of the particle PPM, depending on rho and indices of refraction n(r) a
nd absorption kappa of the particle material, was conducted. It was sh
own that, at kappa rho much less than 1, the PPM of such particles has
a negative value, and, at kappa rho > 1, it has a positive value.