| Single submicron droplet evaporation rates have been measured precisely by means of a light scattering measurement from a charged droplet suspended in the path of a laser in an electric field. Ultra low vapor pressures and Lennard-Jones potential parameters of dioctyl phthalate (DOP), dibutyl phthalate (DBP), and dibutyl sebacate (DBS) have been determined from the light scattering data by comparing them with Mie theory. Diffusivities and heats of vaporization of DOP, DBP, and DBS are also obtained from the diffusion-controlled evaporation rate data. A mathematical model for the diffusion-controlled binary droplet evaporation has been developed and has been tested experimentally with light scattering measurements from DBP/DOP binary mixture starting with various initial droplet compositions. An electrodynamic balance has been built into a light scattering photometer and used to study binary droplet evaporation. Size, mass and optical properties of single solid or liquid charged spherical and nonuniform particles have been determined by using this "picobalance". Refractive index and size of three Dow polystyrene particles (1.011 (mu)m, 5.7 (mu)m, 11.9 (mu)m nominal dia.) have been determined in this way. The complex index of refraction and equivalent sphere size and absorption coefficients of dust particles have been determined by comparing the measured light scattering profiles with Mie theory for spheres by means of a non-linear least squares fit known as Levenberg-Marquardt algorithm. Size, real and imaginary parts of the refractive index of the solid particles encountered here have been optimized using this computer code. Results obtained in this study have been compared with existing data and empirical correlations where available. |
