Relaxation dynamics of pure and doped He nanodroplets probed by EUV-UV pump-probe ionization at the free-electron laser FERMI

该项目的目标是利用EUV-UV泵浦探针实验，在意大利的里雅斯特第一台种子自由电子激光器FERMI@Elettra上全面解决超流氦纳米液滴的弛豫动力学。由于其独特的特性（窄带，可调谐，超短脉冲，同步到近红外到紫外激光脉冲），这种激光器非常适合。在规定的束流时间内，利用光离子质谱法和光电子成像检测，研究了附着在He液滴上的掺杂剂的各种弛豫通道，如带内和带间的振动弛豫、二聚化、自由Rydberg原子的发射、自离子化以及Penning电离。强相关动力学的开始，如多液滴激发，随后的激子湮灭和集体自离化将被表征。

The goal of this project is to fully resolve the relaxation dynamics of superfluid helium nanodroplets using EUV-UV pump-probe experiments at the first seeded free-electron laser FERMI@Elettra in Trieste, Italy. This laser is ideally suited owing to its unique features (narrow-band, tunable, ultra-short pulses, synchronization to NIR up to UV laser pulses). Within the approved beamtime, various relaxation channels such as intra- and inter-band vibronic relaxation, dimerization, emission of free Rydberg atoms, autoion-ization, as well as Penning ionization of dopants attached to He droplets will be studied using photoion mass spectrometry and photoelectron imaging detection. The onset of strongly correlated dynamics such as multiple droplet excitation followed by exciton annihilation and collective autoion-ization will be characterized.