Investigation of regeneration effect of blue luminescence in NaCl using variable delay optically stimulated luminescence (VD-OSL)

• Optically stimulated luminescence (OSL) of sodium chloride (NaCl) was studied.
• Regeneration of the OSL signal was found for subsequent measurements.
• New method – the variable delay OSL measurement (VD-OSL) was invented.
• VD-OSL allows to study OSL kinetics at very long time scale.
• VD-OSL data confirm coexistence of both regeneration and fading in NaCl.

Optically stimulated luminescence (OSL) of pure analytical sodium chloride (NaCl) was studied. Performing series of CW-OSL (continuous wave OSL) readouts it was found that subsequent CW-OSL decay, after some delay, starts from significantly higher intensity level than the final intensity of the previous readout. To study this ‘regeneration effect’ a new type of measurements was implemented – the variable delay OSL (VD-OSL) method. The idea of VD-OSL is explained – it allows to study OSL kinetics at very long time scale. VD-OSL data confirm coexistence of two effects in NaCl – regeneration and fading of the OSL signal. After partial CW-OSL readout, regeneration predominates in the short time scale of the order of 103 s. Then, fading becomes dominant. The same measurements were applied to commonly used Al2O3:C material as well. Nevertheless, the results do not show such behavior at the studied time scale. Theoretical arguments are presented that the regeneration mechanism cannot be explained on the basis of the simple trap model.