Light scattering instrumentation for aerosol studies: An historical overview

The most powerful and elegant method for determining particle size distributions of aerosols by light scattering is to observe single particles suspended in a Millikan-Fletcher electrostatic field. The first such light scattering studies were carried out by Whytlaw-Gray and Patterson (1926), by Gucker and Egan (1961), and then by Wyatt and Phillips (1972). Optically levitated particles were studied by Grehan and Gousebet (1986). Optical particle counters were devised by Gucker and his associates (1947a,b) and Gucker and Rose (1954) for both forward and 90 degrees viewing. Gucker also built an instrument for on-line viewing of 360 degrees scatter by particles flowing through a light beam in single file. Individual particles were also analyzed in an ultramicroscope by Wells and Gerke (1919). The earliest angular scattering patterns from assemblies of particles were by Tolman anti Vliet (1921) and by Sinclair and La Mer (1949). Other interesting systems have utilized acoustic detectors, power loss in a laser cavity, and Doppler shifted light scattering signals. (C) 1997 American Association for Aerosol Research.