Computational Aspects of Photon Correlation Spectroscopy: The Histogram Method

Abstract

The purpose of this study was to write the computer programs necessary to apply the Histogram Method for analyzing correlation functions obtained from Photon Correlation Spectroscopy and also to test how well this method performs. The reason why The Upjohn Company was interested in developing this technique was the ability of the Histogram Method to extract more information from Photon Correlation Spectroscopy than previously possible. By analyzing correlation functions one can obtain the radii of particles suspended in a solution. This information can be used to characterize particles suspended in a solution. The method currently being used to analyze correlation functions by The Upjohn Company, the Cummulants Method, produces only a mean radius and its standard deviation. The Histogram Method on the other hand produces a distribution of radii. This becomes increasingly more important as one moves to solutions with particles of different sizes. When one analyzes the correlation function obtained for a solution containing two different size particles the Cummulants Method gives a radius somewhere between the two. The Histogram Method will however will distinguish between the two particles and produce a size distribution which more accurately reflects the actual sizes of the particles present.