Time-resolved studies of the interactions between pulsed lasers and aerosols

Studies of the interaction between a pulsed CO2 laser and micrometer-sized aqueous and organic particles by use of light-scattering methods and step-scan Fourier-transform infrared (FTIR) spectroscopy are reported. Visible two-color extinction experiments indicate primary particle shattering, accompanied by a high fraction of vaporization, followed by secondary particle evaporation. The extent of the latter depends on the pulse intensity and particle composition. Angle-resolved light-scattering investigations provide insight into the aerosol size distribution and temperature following the pulsed heating event. The time dependence of the vapor plume, monitored with step-scan FTIR spectroscopy, confirms that a large fraction of the initial particle is quickly evaporated during the shattering event, followed by secondary fragment evaporation and thermal expansion.