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

• 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. © 2018 The Author(s).

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Annan elektroteknik och elektronik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Other Electrical Engineering, Electronic Engineering, Information Engineering (hsv//eng)

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Keyword

Angular distribution

Electric fields

Free electron lasers

Laser pulses

Light sources

Modulation

Optical pumping

Photoelectrons

Photons

Pumping (laser)

X rays

Attosecond resolution

Circularly polarized

Instantaneous frequency

Ionization continuum

Linac Coherent Light Source

Photoelectron energy

Self-amplified spontaneous emission

X-ray free electron lasers

Electrons

Publication and Content Type

ref (subject category)

art (subject category)