During an electromagnetic irradiation (UV), the coloration of alpha -Al2O3
material is modified. With cathodoluminescent experiments, specification of
the electronic rearrangement which is induced by the UV irradiation has be
en tried. The quantity of electrical charges which can be trapped in the sa
pphire to determine how the electronic state of the structural defects can
modify the trapping capacity has also been measured. (C) 2001 Published by
Elsevier Science B.V.