Understanding delayed fluorescence and triplet decays of Protoporphyrin IX under hypoxic conditions

Marek Scholz, Gauthier Croizat, Jakub Pšenčík, Roman Dědic, Santi Nonell, Georges Wagnieres

Research output: Indexed journal article Articlepeer-review

3 Citations (Scopus)


Photosensitizers of singlet oxygen exhibit three main types of reverse intersystem-crossing (RISC): thermally activated, triplet-triplet annihilation, and singlet oxygen feedback. RISC can be followed by delayed fluorescence (DF) emission, which can provide important information about the excited state dynamics in the studied system. An excellent model example is a widely used clinical photosensitizer Protoporphyrin IX, which manifests all three mentioned types of RISC and DF. Here, we estimated rate constants of individual RISC and DF processes in Protoporphyrin IX in dimethylformamide, and we showed how these affect triplet decays and DF signals under diverse experimental conditions, such as a varying oxygen concentration or excitation intensity. This provided a basis for a general discussion on guidelines for a more precise analysis of long-lived signals. Furthermore, it has been found that PpIX photoproducts and potential transient excited complexes introduce a new overlapping delayed luminescence spectral band with a distinct lifetime. These findings are important for design of more accurate biological oxygen sensors and assays based on DF and triplet lifetime.

Original languageEnglish
Pages (from-to)843-857
Number of pages15
JournalPhotochemical and Photobiological Sciences
Issue number7
Publication statusPublished - Jul 2021


Dive into the research topics of 'Understanding delayed fluorescence and triplet decays of Protoporphyrin IX under hypoxic conditions'. Together they form a unique fingerprint.

Cite this