Attosecond time-energy structure of X-ray free-electron laser pulses

作者：Hartmann N^*; Hartmann G; Heider R; Wagner M S; Ilchen M; BucK J; Lindahl A O; Benko C; Gruenert J; Krzywinski J; Liu J; Lutman A A; Marinelli A; Maxwell T; Miahnahri A A; Moeller S P; Planas M; Robinson J; Kazansky A K; Kabachnik N M; Viefhaus J; Feurer T; Kienberger R; Coffee R N; Helml W^*

来源：Nature Photonics, 2018, 12(4): 215-+.

DOI：10.1038/s41566-018-0107-6

The time-energy information of ultrashort X-ray free-electron laser pulses generated by the Linac Coherent Light Source is measured with attosecond resolution via angular streaking of neon 1s photoelectrons. The X-ray pulses promote electrons from the neon core level into an ionization continuum, where they are dressed with the electric field of a circularly polarized infrared laser. This induces characteristic modulations of the resulting photoelectron energy and angular distribution. From these modulations we recover the single-shot attosecond intensity structure and chirp of arbitrary X-ray pulses based on self-amplified spontaneous emission, which have eluded direct measurement so far. We characterize individual attosecond pulses, including their instantaneous frequency, and identify double pulses with well-defined delays and spectral properties, thus paving the way for X-ray pump/X-ray probe attosecond free-electron laser science.

• 出版日期2018-3