一种用于50千赫重复频率的极紫外超快角分辨光电子能谱的装置。

A setup for extreme-ultraviolet ultrafast angle-resolved photoelectron spectroscopy at 50-kHz repetition rate.

作者信息

Buss Jan Heye, Wang He, Xu Yiming, Maklar Julian, Joucken Frederic, Zeng Lingkun, Stoll Sebastian, Jozwiak Chris, Pepper John, Chuang Yi-De, Denlinger Jonathan D, Hussain Zahid, Lanzara Alessandra, Kaindl Robert A

机构信息

Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

出版信息

Rev Sci Instrum. 2019 Feb;90(2):023105. doi: 10.1063/1.5079677.

DOI:10.1063/1.5079677

PMID:30831755

Abstract

Time- and angle-resolved photoelectron spectroscopy (trARPES) is a powerful method to track the ultrafast dynamics of quasiparticles and electronic bands in energy and momentum space. We present a setup for trARPES with 22.3 eV extreme-ultraviolet (XUV) femtosecond pulses at 50-kHz repetition rate, which enables fast data acquisition and access to dynamics across momentum space with high sensitivity. The design and operation of the XUV beamline, pump-probe setup, and ultra-high vacuum endstation are described in detail. By characterizing the effect of space-charge broadening, we determine an ultimate source-limited energy resolution of 60 meV, with typically 80-100 meV obtained at 1-2 × 10 photons/s probe flux on the sample. The instrument capabilities are demonstrated via both equilibrium and time-resolved ARPES studies of transition-metal dichalcogenides. The 50-kHz repetition rate enables sensitive measurements of quasiparticles at low excitation fluences in semiconducting MoSe, with an instrumental time resolution of 65 fs. Moreover, photo-induced phase transitions can be driven with the available pump fluence, as shown by charge density wave melting in 1T-TiSe. The high repetition-rate setup thus provides a versatile platform for sensitive XUV trARPES, from quenching of electronic phases down to the perturbative limit.

摘要

时间分辨和角分辨光电子能谱（trARPES）是一种用于追踪准粒子和电子能带在能量和动量空间中超快动力学的强大方法。我们展示了一种用于trARPES的装置，它具有重复频率为50 kHz的22.3 eV极紫外（XUV）飞秒脉冲，能够进行快速数据采集，并以高灵敏度获取动量空间中的动力学信息。详细描述了XUV光束线、泵浦 - 探测装置和超高真空终端站的设计与操作。通过表征空间电荷展宽的影响，我们确定了最终的源极限能量分辨率为60 meV，在样品上的探测通量为1 - 2×10光子/秒时，通常可获得80 - 100 meV的分辨率。通过对过渡金属二卤化物的平衡和时间分辨ARPES研究展示了该仪器的性能。50 kHz的重复频率使得能够在半导体MoSe中以低激发通量对准粒子进行灵敏测量，仪器的时间分辨率为65 fs。此外，如在1T - TiSe中电荷密度波熔化所示，可用的泵浦通量能够驱动光诱导相变。因此，这种高重复频率装置为灵敏的XUV trARPES提供了一个通用平台，可用于从电子相的猝灭到微扰极限的研究。