Light-induced evolution of an aerosol particle

摘要

Let us consider a spherical particle suspended in a mixture consisting of the vapor of this particle and a noncondensing gas.The radius of the particle is much greater than the radius of a critical nucleation center.We irradiate the system with monochromatic light.The particle is absorbed the optical radiation,it heats up,thus destroying the phase equilibrium,and begins to evaporate [1].Let the frequency of the traveling light wave is close to the absorption line of the electronic or vibrational-rotational transition of vapour molecules.Due to the Doppler effect,only the vapour molecules whose velocity projection on the radiation direction lines within a certain velocity range can be excited.The excited molecules change their transport properties - in particular,the collision cross section.If excited and nonexcited vapour molecules interact with molecules of the buffer (nonabsorbing and noncondensing)gas differently,the distribution function for the vapour molecules becomes nonequilibrium.As a result the temperatures of the vapour and the vapour-gas mixture are different (resonant heating or cooling of the vapour)[2].When the vapour temperature is higher than the temperature of the system,the particle is evaporated.In the opposite case the condensation growth of the particle takes place [3].