Zhang Xian-Yi

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.

Investigation of ultrafast dynamics of CdTe quantum dots by femtosecond fluorescence up-conversion spectroscopy

The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence up-conversion spectroscopy. Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time of ~ 1.6 ps with exciting at 400 nm, depending on the state of the photo-excited hole. The shallow trapped states and deep trap states in the forbidden gap are confirmed for CdTe quantum dots. In addition, Auger relaxation of trapped carriers is observed to occur with a time constant of ~ 5 ps. A schematic model of photodynamics is established based on the results of the spectroscopy studies. Our work demonstrates that femtosecond fluorescence up-conversion spectroscopy is a suitable and effective tool in studying the transportation and conversion dynamics of photon energy in a nanosystem.

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。