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Fig. 3 | Nanoscale Research Letters

Fig. 3

From: Photodynamic Therapeutic Effect of Nanostructured Metal Sulfide Photosensitizers on Cancer Treatment

Fig. 3

Generation of reactive oxygen species and excited states of the photosensitizer. Light promotes the excitation of an electron from a low-energy singlet state (So) to high-energy singlet states (S1,2). Such states can lose their energy via fluorescence (radiative emission, light) or internal conversion (non-radiative emission, heat). The spin flipping of the high-energy electron takes places via intersystem crossing, which leads to a long-lived excited triplet state (T1). Type I and II reactions favor the formation of free radicals and singlet oxygen (1O2), respectively, in the presence of 3O2. Significantly modified from Ref. [11]

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