  In this paper a differential equation with noninteger order was used to model
an anomalous luminescence decay process. Although this process is in principle
an exponential decaying process, recent data indicates that is not the case for
longer observation time. The theoretical fractional differential calculus
applied in the present work was able to describe this process at short and long
time, explaining, in a single equation, both exponential and non-exponential
decay process. The exact solution found by fractional model is given by an
infinite serie, the Mittag-Leffer function, with two adjusting parameters. To
further illustrate this nonexponential behaviour and the fractional calculus
framework, an stochastic analysis is also proposed.
