Xu Xinsheng

A Time‐Resolved Electron Spin Resonance Study of the Generation Mechanism of the Benzoquinone Anion Radical

Abstract The chemically induced dynamic electron polarization (CIDEP) spectra for the photolysis of the p‐benzoquinone (PBQ)/formamide (FM) system in acid, basic, and micellar environments were obtained with a homemade time‐resolved electron spin resonance (TR‐ESR) spectrometer. When the PBQ/formamide was photolyzed, the CIDEP spectrum consisted of strong CIDEP signals of the benzosemiquinone anion radical PBQ•− and weak signals for the benzosemiquinone neutral radical PBQH•. When the PBQ/formamide was irradiated in basic or micellar solution, the CIDEP signal for PBQ•− only was obtained. When the PBQ/formamide was irradiated in acid solution, only the CIDEP signal of PBQH• existed. These experimental results indicate that the anion radical PBQ•− was formed from the dissociation of the neutral radical PBQH• accompanying polarization transfer.

Theoretical study of hyperfine related CIDEP of radical-triplet pairs

Considering the interaction between excited triplet molecule and doublet radical, based on the second-order perturbation theory and the motion equation of density matrix, the spin polarization intensity on the radical was theoretically calculated. The results of calculation indicate that the polarization was hyperfine related. With the overpopulation on doublet spin states of radical–triplet pairs as initial condition, the CIDEP on the radicals were A + A/E pattern and with the overpopulation on quartet spin states of radical–triplet pairs, the CIDEP was E + E/A pattern.

Transient Electron Polarization of Anthraquinone/Hydrogendonor/2,2,6,6tetramethylpiperidinyloxyl

用时间分辨电子自旋共振波谱仪研究了光解蒽醌／乙二醇、蒽醌／乙二醇／氮氧自由体系的化学诱导动态电子自旋极化，实验结果指出，在蒽醌／乙二醇／氮氧自由基（AQ／EG／TEMPO）体系中，存在自由基三重点对（RPTM）和三重态（TM）极化的竞争，并由此讨论了三重态－自由基对的反应速率。