Radiation-induced defect formation in fluoride crystals such as magnesium fluoride (MgF 2 ) has been extensively studied due to its importance in optical systems operating under extreme radiation environments. Under irradiation by gamma rays, electrons, neutrons, and energetic ions, these materials exhibit ionoluminescence (IL) associated with the formation of vacancies and color centers. The study of this IL produces valuable insight into the mechanisms governing radiation-induced damage. In this work, we present a novel in-situ optical monitoring system capable of continuously tracking IL emissions during irradiation with high temporal resolution, enabling direct observation of defect evolution in real time. Using this system, IL response of MgF 2 under different ion irradiations spanning a range of electronic stopping powers (0.15 to 3 keV/nm) was investigated. The results reveal a strong dependence of the emission spectra on the stopping power of the incident ions, highlighting the critical role of local energy deposition in the formation and evolution of luminescent defect centers. These findings demonstrate the potential of real-time IL monitoring as a powerful operando technique for studying radiation-induced dynamic defects in fluoride materials as well as possible non-studied transition between emission bands in MgF 2 .
Valls-Vicent et al. (Wed,) studied this question.