Luminescence of photoactivated pristine and Cr-doped MgAl2O4 spinel

- Emission of pristine and Cr-doped MgAl2O4 spinel induced by different mechanisms.
- Cr-doping alters major pathway of physical relaxation through luminescence.
- Quenching of luminescence associated with intrinsic defects.
- Mechanism of PhICL emission due to electron transfer.
- Energy transfer pathway for PhICL not precluded.