Thulium as a monitor of lattice damage in cadmium sulphide

The Tm 3+ sharp line emission spectrum at 10 K in cadmium sulphide has been shown to be very sensitive to electron radiation damage at sample temperatures above 320 K and at incident electron energies above 114 keV (identical with 8·7 eV sulphur displacement threshold energy). Changes in the rare earth emission spectra result from the production of complex centres involving thulium ions and sulphur defects. The radiation-induced defects can be removed completely by warming the sample to temperatures greater than 420 K, and activation energies for annealing have been determined.