Radioluminescence of alkaline ices

The reactions of electrons in alkaline glasses containing 5 to 20 M NaOH were studied by isothermal luminescence (ITL) after γ-irradiation at 77 K and by radiothermoluminescence (RTL). Both ITL and total RTL emission are influenced by NaOH concentration in a similar way revealing a minimum at 8 to 10 M NaOH. The RTL emission exhibits two broad peaks. The low temperature peak is only slightly dependent on matrix composition. The position of the high temperature peak shifts with the glass transition point of the matrix. The contributions of these peaks to the total RTL emission can be correlated with concentration of trapped electrons (e-sub(t)), H atoms, (Na+...e-)sub(t) pairs and O- radicals. It is suggested that ITL and the low temperature RTL peak are possibly due to the radiative tunnelling of e-sub(t) to H atoms and radiative capture of electrons by alkali metal cations. The former mechanism is dominant for matrices containing less than 8 M NaOH, the latter for the higher concentrations of solute. The high temperature RTL peak is mainly associated with the radiative recombination of e-sub(t) with O- radicals. (author)