Thermoluminescence study of the amorphisation of hexagonal ice by irradiation at 77 K

This paper reports on a thermoluminescence study of D₂O ice I_h. A sample of hexagonal (I_h) ice is irradiated by a 100 MeV X-ray source at 77 K. The emission spectrum that is measured immediately after the end of the irradiation process has the thermoluminescent behaviour of amorphous ice. The kinetic transition is followed to the stable form, taking place at 85 K. The relaxation time of the transition is of the order of 5 minutes. It is concluded that, due to irradiation, a few outer layers of ice I_h are converted to the low-density amorphous form of ice, which then converts to cubic ice. Although complex to quantify, thermoluminescence appears to be, in the present study, particularly sensitive to the time evolution of irradiated samples.