Abstract
We irradiated outgassed methylcyclohexane glass containing biphenyl (concentration 10−4 to 10−2 mol. dm3) with γ-rays (dose rate 60 krad h−1, dose 30 krad) in liquid helium and started recording the luminescence emitted 4 min after the end of irradiation. An isothermal decay was observed at 4.2 K for more than 3 h. On subsequent warming the light output increased and the two well known thermoluminescence peaks were observed at 90 and 95 K. In all experiments the integrated light emission during the first 25 min of the decay at 4.2 K amounted to 3±1% of the total deferred luminescence. Blank experiments showed that the luminescence observed at 4.2 K was not due to residual nitrogen. As kT at 4.2 K is only 3.6×10−4 eV, thermal detrapping of electrons seems to be excluded at this temperature. Hence it seems that deferred luminescence observed at 4.2 K must be ascribed to tunnelling of electrons trapped very near the cations, probably at a distance less than 15Å. Measurements of decay kinetics and of the influence of the matrix are in progress.
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KIEFFER, F., MAGAT, M., MEYER, C. et al. Deferred Luminescence at 4.2 K in an Organic Glass. Nature Physical Science 232, 130 (1971). https://doi.org/10.1038/physci232130a0
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DOI: https://doi.org/10.1038/physci232130a0