X-ray free-electron lasers

Abstract

In a free-electron laser (FEL) the lasing medium is a high-energy beam of electrons flying with relativistic speed through a periodic magnetic field. The interaction between the synchrotron radiation that is produced and the electrons in the beam induces a periodic bunching of the electrons, greatly increasing the intensity of radiation produced at a particular wavelength. Depending only on a phase match between the electron energy and the magnetic period, the wavelength of the FEL radiation can be continuously tuned within a wide spectral range. The FEL concept can be adapted to produce radiation wavelengths from millimetres toÅngstroms, and can in principle produce hard x-ray beams with unprecedented peak brightness, exceeding that of the brightest synchrotron source by ten orders of magnitude or more. This paper focuses on short-wavelength FELs. It reviews the physics and characteristic properties of single-pass FELs, as well as current technical developments aiming for fully coherent x-ray radiation pulses with pulse durations in the 100 fs to 100 as range. First experimental results at wavelengths around 100 nm and examples of scientific applications planned on the new, emerging x-ray FEL facilities are presented.

Synchrotron ultrafast techniques for photoactive transition metal complexes

“…However, for the time being, this apparently simple solution is not feasible since, for q > 7 Å −1 , the experimental q I(q) data are dominated by noise and the interval 4 Å −1 < q < 7 Å −1 is too limited for extracting any reliable structural information. This situation will change in the future, with the availability of hard X-ray free electron lasers (FELs) [220][221][222][223][224][225][226][227][228][229], where the number of photons per electron pulse will reach values as high as 10 12 , compared with 10 6 for third-generation synchrotron radiation sources.…”

Precision calculation of above-threshold multiphoton ionization in intense short-wavelength laser fields: The momentum-space approach and time-dependent generalized pseudospectral method

“…The pulse shape is the same as that used in the previous subsection and is given by Eq. (34). The angular frequency of this laser is ω = 0.5 a.u.…”

“…With the recent development of intense and ultrashort-wavelength free-electron lasers [32][33][34], the study of multiphoton * zyzhou@ku.edu † sichu@ku.edu processes in the high-frequency and strong-field regime becomes increasingly important [35][36][37]. In such a regime, the electron can achieve very high energy by absorbing photons from the fields and can go very far from the nucleus.…”

Atomic plasma excitations in the field of a soft x-ray laser

“…The highly intense and ultra-short soft and hard x-ray laser pulses allow time-resolved imaging of advanced materials with femtosecond resolution for many applications [4][5][6][7]. It concerns, for example, the investigation of fast chemical reactions on surfaces or within biological systems by means of microscopic snapshots.…”