Pulse-height light-scatter distributions using flow-systems instrumentation.

Several laboratories have recently been making light-scatter measurements on cells and other particles using flow-systems instrumentation. We at the Los Alamos Scientific Laboratory, as well as others, have obtained multimodal pulse-height distributions in certain angular regimes from particles of supposedly uniform characteristics. Because it was assumed that multimodal distributions implied characteristics of multivalue, the accuracy of such data has been doubted. In the present work, pulse-height distributions anticipated on the basis of exact electromagnetic theory were calculated for particles of known characteristics. These calculated pulse-height distributions agree quite well with those obtained experimentally. Physical optics form the basis for the explanation of the complex pulse-height distributions obtained experimentally. However, the results of this study show that certain cautions are necessary in the interpretation of light-scatter data presented in this manner.