Laser-induced Breakdown Detection (LIBD) for the highly sensitive quantification of aquatic colloids.: Part I:: Principle of LIBD and mathematical model

A new type of Laser-induced Breakdown Detection (LIBD) is being developed for the direct quantification of aquatic colloids of extremely small sizes at very low concentrations, which are not detectable by the commercial methods currently available. LIBD allows for the detection of colloids in the lower nanometer range. Different statistical and mathematical models are available for the quantification of colloids in aquatic systems. In this double publication (parts I and II), a model based on binomial statistics was employed. This is introduced as the basis of our theoretical descriptions of the experimental data discussed in part II. As a prerequisite, a qualitative and quantitative description of the power density distribution in the focal area of a laser beam is necessary and thus is also presented in this article. Together with the second part, this paper is intended to provide a profound insight into both the theoretical and experimental aspects of the Laser-induced Breakdown Detection technique, and to show practical applications as well as the latest developments in this field of particle characterization.