Time-resolved low energy photoelectron diffraction for the study of surface structural dynamics with sub-100 fs temporal resolution

用于研究表面结构动力学的时间分辨低能光电子衍射，时间分辨率低于 100 fs

• 批准号: 433458487
• 负责人: Professor Dr. Michael Bauer
• 金额: --
• 依托单位: Institut für Experimentelle und Angewandte Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/433458487?language=en
• 关键词: Time; resolved; low; energy; photoelectron

Based on the diffraction of low energy photoelectrons we aim for proving and applying a novel experimental concept for the study of ultrafast structural dynamics at surfaces with sub-100 fs temporal resolution. Next to structural information, the detected transient photoemission signal will at the same time carry information about excitation and relaxation of the involved surface electronic system potentially allowing for a direct correlation of structural and carrier dynamics at surfaces. Within our studies we will focus on sub-monolayer adsorption of phthalocyanine molecules on noble metal surfaces. The distinctive low energy photoelectron diffraction patterns that have been reported for different representatives of this adsorbate-surface system in static ARPES experiments represent an ideal test bed for the examination of the capabilities and limitations of the proposed concept. Furthermore, we expect that the combined interrogation of structural and carrier dynamics can shed new light into the complex interaction mechanisms governing the multifaceted properties of this metal-organic interface class. Two different experimental configurations will be realized and tested within the project: In using 70 fs NUV laser pulses (6 eV) for the generation of the probing photoelectrons we will be able to probe structural and carrier dynamics at an ultimate temporal resolution below 100 fs. The intrinsic very low kinetic energies of the photoelectrons of Ekin < 2 eV will, however, limit our studies to small and moderate pump fluences due to a signal background arising from pump-induced parasitic electron emission. In an alternative configuration we will use 18 eV vacuum ultraviolet pulses from a HHG source so that also experiments at significantly higher pump fluences will become possible. In this fluence regime we expect to be able to trigger also structural phase transitions in the adsorbate layer.

基于低能光电子的衍射，我们的目标是证明和应用一个新的实验概念，在表面的超快结构动力学的研究与亚100 fs的时间分辨率。除了结构信息之外，检测到的瞬态光电发射信号将同时携带关于所涉及的表面电子系统的激发和弛豫的信息，潜在地允许表面处的结构和载流子动力学的直接相关。 在我们的研究中，我们将集中在酞菁分子在贵金属表面的亚单层吸附。独特的低能量光电子衍射图案，已被报道为不同的代表，这种吸附物表面系统在静态ARPES实验代表了一个理想的试验台，用于检查的能力和所提出的概念的局限性。此外，我们预计，结构和载体动力学的组合审讯可以揭示新的光到复杂的相互作用机制，这种金属-有机界面类的多方面性能。两种不同的实验配置将在该项目中实现和测试：在使用70 fs的NUV激光脉冲（6 eV）的探测光电子的产生，我们将能够探测结构和载流子动力学的最终时间分辨率低于100 fs。然而，Ekin < 2 eV的光电子的固有非常低的动能将限制我们的研究，由于泵浦诱导的寄生电子发射产生的信号背景，小和中等的泵浦注量。在另一种配置中，我们将使用来自HHG源的18 eV真空紫外脉冲，这样在显著更高的泵浦注量下的实验也将成为可能。在这种注量制度，我们希望能够触发也在吸附层的结构相变。