In the process of optical stimulation the emission of luminescence is, in principle, intrinsically more sensitive than thermally stimulated process. Moreover, the optical nature of the procedure obviates the necessity to heat the dosimetric material and simplifies the instrumentation. Recently, anion-deficient aluminum oxide doped with carbon (α-Al2O3:C) is proposed as a suitable photoluminescent material. The important and useful aspect of PL is that unique meta-stable color center defects are created through the action of incident ionizing radiation, that permit quantification of the exposure or dose delivered to the phosphor. The purpose of this study is to investigate the excitation wavelength dependence of the PL intensity when irradiated in the fields of variable specific ionization density. The results of experiment that strong excitation peak at shorter wavelengths due to the relaxation of charge from F2 center was examined. This suggests the ability to extend the useful range of wavelength used in the stimulation of PL and to use the F2 centers for storage of dosimetric information. It is thought prudent to apply the excellent work from basic research for radiation dosimetry applications especially for mixed radiation fields having variable specific ionization densities.