Method to measure time-dependent scattering cross sections of particles evaporating in a laser beam

Abstract: We develop a new method of measuring the time-dependent solid angle scattering cross section for detection of individual particles flowing across a Gaussian laser beam. This method is based on the principle that the normalized derivative of the scattering signal measured by an instrument can be decomposed into the normalized derivative of the incident irradiance and that of the scattering cross section . For evaporative particles, holds true until evaporation starts at a certain position in the laser beam. The for individual particles is determined from , which is extracted from . is derived from and . We apply the method to particles with and without evaporation using a single-particle soot photometer. The robustness of the method is confirmed through results for non-evaporative particles. For evaporative particles, derived values before the onset of evaporation are compared to Mie theory. [Copyright &y& Elsevier]