Ultrafast Electronic and Molecular Dynamics Induced by Ultrashort FEL Pulses

Kiyoshi Ueda

Research output: Contribution to journalArticlepeer-review


In recent years, short wavelength free electron lasers (FELs) have opened up access to ultrafast electronic and structural dynamics in matter. Currently, four FEL facilities are in operation in the world. FLASH [1] in Germany and FERMI [2] in Italy cover the range from extreme ultraviolet (EUV) to soft X-rays, while LCLS [3] in the U.S. and SACLA [4] in Japan provide pulses in the hard X-ray regime. In addition, an upgrade version of SCSS [5], nicknamed SCSS+, has also just started user operation as a beamline of SACLA [6]. These FELs deliver coherent pulses combining unprecedented power densities up to ~1020 W/cm2 and extremely short pulse durations down to a few femtoseconds. The intense coherent FEL pulse focused down to ~1 μm2 makes single-shot diffractive imaging of nano-crystals or even non-crystallized bio-samples as well as other small objects a reality. Time-resolved spectroscopic and structural studies on the timescale of femtoseconds, having FEL pulses as a probe, allow us to probe electrons and atoms in action. Additionally, since FEL pulses are in a new regime of intensity, they are opening up new research fields that exploit the interaction between intense short wavelength pulses and matter, leading to matter at extremely high energy. Relevant theories dealing with such extreme conditions are also rapidly growing.

Original languageEnglish
Pages (from-to)3-7
Number of pages5
JournalSynchrotron Radiation News
Issue number5
Publication statusPublished - 2016 Sep 2

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Nuclear and High Energy Physics


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