Figure 3 | Scientific Reports

Figure 3

From: Ultraviolet A irradiation induces ultraweak photon emission with characteristic spectral patterns from biomolecules present in human skin

Figure 3

Scheme of the proposed mechanism of UPE generation in the skin by UVA irradiation. UVA irradiation causes UPE generation through oxidation of biomolecules in the skin via several pathways. Biomolecules exposed to UV directly generate UPE, while photosensitizers in the skin are excited by UV exposure. The excited photosensitizers oxidize biomolecules, and UPE is generated via the photosensitization reaction. The excited photosensitizer itself can act as a UPE source too. The UPE measured by the spectroscopy system, therefore, must have comprised the UPE from each of these pathways with a broad spectral pattern that peaked at 530–580 nm.

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