Time-resolved photoelectron spectroscopy of low-energy excitations of 4×4 C60/Cu(111).
Time-resolved photoelectron spectroscopy of low-energy excitations of 4×4 C60/Cu(111).
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4×4 C60/Cu(111)低能激发的时间分辨光电子能谱。
DOI：
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发表时间：
2010
影响因子：
4.4
通讯作者：
H. Zacharias
中科院分区：
文献类型：
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作者：
A. Rosenfeldt;B. Göhler;H. Zacharias
采用时间分辨双光子光电发射技术研究了铜衬底上有序富勒石多层单层中的电子动力学。采用耦合激发态动力学对实验数据进行了分析。在表面温度为140 K时，符合这些动力学方程的最低未占据分子轨道（LUMO）的寿命约为80 ps，单重态激子的寿命约为1.2 ns，三重态激子的寿命约为22 μs。捕获的三重态激子寿命可达200 μs。由于湮灭，激发通量的增加降低了激子的寿命。样品温度的升高会略微降低三重态激子的寿命。在hν = 2.9 ~ 3.3 eV范围内，激子寿命与泵浦光子能量没有明显的关系。只要制备超过9ml，就不会观察到对层厚度（10- 20ml）的依赖。
Time-resolved two-photon photoemission is applied to investigate electron dynamics in multiple monolayers (MLs) of ordered fullerite on a copper substrate. The experimental data are analyzed assuming coupled excited state dynamics. Rate equations fitted to these dynamics yield lifetimes of about 80 ps for the lowest unoccupied molecular orbital (LUMO), about 1.2 ns for the singlet exciton and 22 μs for the triplet exciton at a surface temperature of 140 K. For trapped triplet excitons lifetimes up to 200 μs are observed. An increased excitation fluence reduces the lifetime of the excitons due to annihilation. An increased sample temperature slightly reduces the lifetime of the triplet exciton. There is no evident dependence of the exciton lifetimes on the pump photon energy in the range of hν = 2.9 to 3.3 eV. A dependence on the layer thickness (10-20 ML) is not observed as long as more than 9 ML are prepared.