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Singlet-Triplet Energy Inversion in Carbon Nitride Photocatalysts |
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| Authors: | Arianna Actis Prof?Dr Michele Melchionna Dr Giacomo Filippini Prof?Dr Paolo Fornasiero Prof?Dr Maurizio Prato Prof?Dr Mario Chiesa Prof?Dr Enrico Salvadori |
| Institution: | 1. Department of Chemistry and NIS Centre, University of Torino, Via Pietro Giuria 7, 10125 Torino, Italy;2. Department of Chemical and Pharmaceutical, INSTM UdR, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy |
| Abstract: | Time-resolved EPR (TR-EPR) demonstrates the formation of well-defined spin triplet excitons in carbon nitride. This permits to experimentally probe the extent of the triplet wavefunction which delocalizes over several tri-s-triazine units. Analysis of the temperature dependence of the TR-EPR signal reveals the mobility of the triplet excitons. By employing monochromatic light excitation in the range 430–600 nm, the energy of the spin triplet is estimated to be ≈0.2 eV above the conduction band edge, proving that the triplet exciton lies above the corresponding singlet. Comparison between amorphous and graphitic forms establishes the singlet-triplet inversion as a general feature of carbon nitride materials. |
| Keywords: | Carbon Nitride EPR Spectroscopy Photochemistry Time-Resolved EPR Triplet State |