Chemiluminescence from UVA-exposed skin: Separating photo-induced chemiluminescence from photophysical light emission

Abstract

Several previous studies have reported luminescence emission from skin following exposure to UVA radiation in air. We show that UVA irradiation of biomaterials and polymers in oxygen, including bovine stratum corneum, followed by photon counting results in a complex emission due to a combination of photophysical processes together with photo-induced chemiluminescence (PICL). The photophysical processes include fluorescence, phosphorescence and charge-recombination luminescence. By irradiating materials in an inert atmosphere such as nitrogen and allowing photophysical light emission to fully decay before admitting oxygen, the weak photo-induced chemiluminescence generated via free radical re..