Actis Arianna, Melchionna Michele, Filippini Giacomo, Fornasiero Paolo, Prato Maurizio, Chiesa Mario, Salvadori Enrico
Department of Chemistry and NIS Centre, University of Torino, Via Pietro Giuria 7, 10125, Torino, Italy.
Department of Chemical and Pharmaceutical, INSTM UdR, University of Trieste, Via Licio Giorgieri 1, 34127, Trieste, Italy.
Angew Chem Int Ed Engl. 2023 Nov 27;62(48):e202313540. doi: 10.1002/anie.202313540. Epub 2023 Oct 23.
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.
时间分辨电子顺磁共振（TR-EPR）表明在氮化碳中形成了明确的自旋三重态激子。这使得能够通过实验探测三重态波函数在几个三嗪单元上离域的程度。对TR-EPR信号的温度依赖性分析揭示了三重态激子的迁移率。通过在430 - 600 nm范围内采用单色光激发，自旋三重态的能量估计比导带边缘高约0.2 eV，证明三重态激子位于相应单重态之上。非晶态和石墨态形式之间的比较确定了单重态 - 三重态反转是氮化碳材料的一个普遍特征。
