The thermoluminescence (TL) of semiconducting diamonds was found to be composed of blue-emitting (at 150 and 260°K) and red-emitting peaks (at 175 and 285°K). The red peaks could be excited by light of wavelengths up to about 650 mμ (1.8 eV), the blue ones by light up to about 420 mμ (3 eV). The intensity of the red peaks and of the 150°K blue peak was found to increase linearly with the dose of excitation. The same was found for the 260°K blue peak on excitation at the absorption edge (225 mμ, 5.5 eV). Excitation of this peak at 260-400 mμ was found to be superlinear; the peak increased under suitable conditions with the third power of the dose of excitation. Other measurements included the thermal activation energies, the optical bleaching of the glow peaks, and the decay of phosphorescence after excitation at 77°K. A tentative model for the energy levels involved in the processes of excitation and emission of the TL is presented to account for the observations. A multiple-stage excitation is proposed to explain the superlinearity.

• Received 30 March 1966

DOI:https://doi.org/10.1103/PhysRev.148.839