Abstract
The main difficulty in solving the corresponding integral expressions for characteristic fluorescence of layered samples consists in the choice of an advantageous approximation of the depth distribution function ϕ (z). In accepting a point source, a linear dependence, or a sum of weighted exponential moments to describe primary excitation, a closed mathematical treatment of secondary excitation effects is possible. Part I of this series is restricted to the frequent case of film substrate samples. The contributing factors of fluorescence excitation are calculated assuming a sum of weighted exponential moments for primary depth distribution and using dimensionless variables. The influence of the shape of primary depth distribution is discussed and can be shown to be less than 5% for bulk conditions.