Dynamics of the fragmentation and ionization of free metal clusters by mild femtosesond laser pulses

温和飞秒激光脉冲对自由金属团簇的破碎和电离的动力学

• 批准号: 20517242
• 负责人: Professor Dr. Bernd von Issendorff
• 金额: --
• 依托单位: Fraunhofer-Institut für Werkstoffmechanik (IWM)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/20517242?language=en
• 关键词: Dynamics; fragmentation; ionization; free; metal

Simple metal clusters with their free-electron-like electronic structure are ideal model systems to study few to many particle dynamcis. The collective electron resonance possible in such systems has a huge electric dipole; for light fields with the right frequency it acts as an antenna producing a strong local amplification of the electric field strength. Off resonance, on the other hand, close to the cluster external fields are significantly screened. This strong modification of the electromagnetic near field by the mobile electron cloud will have a decisive influence on the kinetic energy and angular distribution of emitted electrons or photofragments. In a joint experimental and theoretical study these effects will be examined in detail. Experimentally, the angular resolved kinetic energy distributions of photoelectrons and photofragments after femtosecond laser excitation of free, cold, size selected alkali and noble metal clusters will be measured. On the theory side, time-dependent density functional theory (TD-DFT) and time-dependent tight-binding (TDTB) combined with molecular dynamics calculations will be used to model these nonlinear ionization and fragmentation processes. Especially the newly developed TDTB-MD will allow detailed simulations on the long time scales relevant for fragmentation.

简单金属团簇具有类自由电子的电子结构，是研究少到多粒子动力学的理想模型体系。在这样的系统中，可能的集体电子共振具有巨大的电偶极子;对于具有正确频率的光场，它充当天线，产生电场强度的强烈局部放大。另一方面，离共振近的簇外部场被显著屏蔽。这种由移动的电子云对电磁近场的强烈修改将对发射的电子或光碎片的动能和角分布具有决定性的影响。在一项联合实验和理论研究中，将详细研究这些影响。在实验上，角分辨动能分布的光电子和光碎片后，飞秒激光激发自由，冷，尺寸选定的碱金属和贵金属团簇将被测量。在理论方面，含时密度泛函理论（TD-DFT）和含时紧束缚（TDTB）结合分子动力学计算将被用来模拟这些非线性电离和碎裂过程。特别是新开发的TDTB-MD将允许对与碎裂有关的长时间尺度进行详细模拟。