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Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule is called an ion. Ionization can result from the loss of an electron after collisions with subatomic particles, collisions with other atoms, molecules and ions, or through the interaction with electromagnetic radiation. Heterolytic bond cleavage and heterolytic substitution reactions can result in the formation of ion pairs. Ionization can occur through radioactive decay by the internal conversion process, in which an excited nucleus transfers its energy to one of the inner-shell electrons causing it to be ejected.
An ultrafast monochromator is a monochromator that preserves the duration of an ultrashort pulse. Monochromators are devices that select for a particular wavelength, typically using a diffraction grating to disperse the light and a slit to select the desired wavelength; however, a diffraction grating introduces path delays that measurably lengthen the duration of an ultrashort pulse. An ultrafast monochromator uses a second diffraction grating to compensate time delays introduced to the pulse by the first grating and other dispersive optical elements.
Attosecond physics, also known as attophysics, or more generally attosecond science, is a branch of physics that deals with light-matter interaction phenomena wherein attosecond photon pulses are used to unravel dynamical processes in matter with unprecedented time resolution.
In nonlinear optics, filament propagation is propagation of a beam of light through a medium without diffraction. This is possible because the Kerr effect causes an index of refraction change in the medium, resulting in self-focusing of the beam.
Ultrafast laser spectroscopy is a spectroscopic technique that uses ultrashort pulse lasers for the study of dynamics on extremely short time scales. Different methods are used to examine the dynamics of charge carriers, atoms, and molecules. Many different procedures have been developed spanning different time scales and photon energy ranges; some common methods are listed below.
Ferenc Krausz is a Hungarian-Austrian physicist, whose research team has generated and measured the first attosecond light pulse and used it for capturing electrons’ motion inside atoms, marking the birth of attophysics.
Margaret Mary Murnane NAS AAA&S is Distinguished Professor of Physics at the University of Colorado at Boulder, having moved there in 1999, with past positions at the University of Michigan and Washington State University. She is currently Director of the STROBE NSF Science and Technology Center, and is among the foremost active researchers in laser science and technology. Her interests and research contributions span topics including atomic, molecular, and optical physics, nanoscience, laser technology, materials and chemical dynamics, plasma physics, and imaging science. Her work has earned her multiple awards including the prestigious MacArthur Fellowship award in 2000, the Frederic Ives Medal/Quinn Prize in 2017, the highest award of The Optical Society, and the 2021 Benjamin Franklin Medal in Physics.
The European X-Ray Free-Electron Laser Facility is an X-ray research laser facility commissioned during 2017. The first laser pulses were produced in May 2017 and the facility started user operation in September 2017. The international project with twelve participating countries; nine shareholders at the time of commissioning, later joined by three other partners, is located in the German federal states of Hamburg and Schleswig-Holstein. A free-electron laser generates high-intensity electromagnetic radiation by accelerating electrons to relativistic speeds and directing them through special magnetic structures. The European XFEL is constructed such that the electrons produce X-ray light in synchronisation, resulting in high-intensity X-ray pulses with the properties of laser light and at intensities much brighter than those produced by conventional synchrotron light sources.
Paul Bruce Corkum is a Canadian physicist specializing in attosecond physics and laser science. He holds a joint University of Ottawa–NRC chair in Attosecond Photonics. He is one of the students of strong field atomic physics, i.e. atoms and plasmas in super-intense laser fields.
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Ultrafast electron diffraction (UED), also known as femtosecond electron diffraction (FED), is a pump-probe experimental method based on the combination of optical pump-probe spectroscopy and electron diffraction. UED provides information on the dynamical changes of the structure of materials. It is very similar to time resolved crystallography, but instead of using X-rays as the probe, it uses electrons. In the UED technique, a femtosecond (fs) laser optical pulse excites (pumps) a sample into an excited, usually non-equilibrium, state. The pump pulse may induce chemical, electronic or structural transitions. After a finite time interval, a fs electron pulse is incident upon the sample. The electron pulse undergoes diffraction as a result of interacting with the sample. The diffraction signal is, subsequently, detected by an electron counting instrument such as a CCD camera. Specifically, after the electron pulse diffracts from the sample, the scattered electrons will form a diffraction pattern (image) on a CCD camera. This pattern contains structural information about the sample. By adjusting the time difference between the arrival of the pump and probe beams, one can obtain a series of diffraction patterns as a function of the various time differences. The diffraction data series can be concatenated in order to produce a motion picture of the changes that occurred in the data. UED can provide a wealth of dynamics on charge carriers, atoms, and molecules.
R. J. Dwayne Miller, is a Canadian chemist and a professor at the University of Toronto. His focus is in physical chemistry and biophysics. He is most widely known for his work in ultrafast laser science, time-resolved spectroscopy, and the development of new femtosecond electron sources. His research has enabled real-time observation of atomic motions in materials during chemical processes and has shed light on the structure-function correlation that underlies biology.
High Harmonic Generation (HHG) is a non-perturbative and extremely nonlinear optical process taking place when a highly intense ultrashort laser pulse undergoes an interaction with a nonlinear media. A typical high order harmonic spectra contains frequency combs separated by twice the laser frequency. HHG is an excellent table top source of highly coherent extreme ultraviolet and soft X-ray laser pulses.
Serial femtosecond crystallography (SFX) is a form of X-ray crystallography developed for use at X-ray free-electron lasers (XFELs). Single pulses at free-electron lasers are bright enough to generate resolvable Bragg diffraction from sub-micron crystals. However, these pulses also destroy the crystals, meaning that a full data set involves collecting diffraction from many crystals. This method of data collection is referred to as serial, referencing a row of crystals streaming across the X-ray beam, one at a time.
Linda Young is a distinguished fellow at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and a professor at the University of Chicago’s Department of Physics and James Franck Institute. Young is also the former director of Argonne’s X-ray Science Division.
Ultrafast scanning electron microscopy (UFSEM) is an innovative consolidated facility that combines two microscopic modalities, Pump-probe microscopy and Scanning electron microscope, to gather temporal and spatial resolution phenomena. In fact, this technique is very wonderful at which ultrashort laser will be used for pump excitation of the material and the sample response will be detected by an Everhart-Thornley detector. Acquiring data depends mainly on formation of images by raster scan mode after pumping with short laser pulse at different delay times. The characterization of the output image will be done through the temporal resolution aspect. Thus, the idea is to exploit the shorter DeBroglie wavelength in respect to the photons which has great impact to increase the resolution about 1 nm. That technique is an up-to-date approach to study the dynamic of charge on material surfaces.
Henry N. Chapman FRS is a British physicist and the founding director of the Center for Free-Electron Laser Science at the German Electron Synchrotron (DESY). He has made numerous contributions to the field of x-ray coherent diffraction imaging and is a pioneer of the diffraction before destruction technique that allows to analyze biological samples with intense, ultrafast x-ray light, such as Photosystem II, a key macromolecule in photosynthesis.
References
- ↑ Yarris, Lynn (August 27, 1993). "LBL Beam Test Facility to Yield Ultrafast X-Rays". Ultrafast X-ray diffraction. Lawrence Berkeley National Laboratory. Retrieved 2011-07-08.
- ↑ Corlett, John (August 6, 2010). "Overview of X-Ray FEL R&D at LBNL" (PDF). Lawrence Berkeley National Laboratory. pp. 3, 4, 5. Retrieved 2011-07-08.
- ↑ Siders, C. W.; Cavalleri, A; Sokolowski-Tinten, K; Tóth, C; Guo, T; Kammler, M; Horn Von Hoegen, M; Wilson, KR; et al. (1999). "Detection of Nonthermal Melting by Ultrafast X-ray Diffraction" (PDF). Science. 286 (5443): 1340–1342. doi:10.1126/science.286.5443.1340. PMID 10558985. Free PDF download.
- ↑ Rose-Petruck, Christoph; Jimenez, Ralph; Guo, Ting; Cavalleri, Andrea; Siders, Craig W.; Rksi, Ferenc; Squier, Jeff A.; Walker, Barry C.; et al. (March 25, 1999). "Picosecond–milliångström lattice dynamics measured by ultrafast X-ray diffraction" (PDF). Nature. 398 (6725): 310–312. Bibcode:1999Natur.398..310R. doi:10.1038/18631. S2CID 4399550. Free PDF download.
- ↑ Zamponi, F.; Ansari, Z.; Woerner, M.; Elsaesser, T. (2010). "Femtosecond powder diffraction with a laser-driven hard X-ray source" (PDF). Optics Express. 18 (2): 947–61. Bibcode:2010OExpr..18..947Z. doi: 10.1364/OE.18.000947 . PMID 20173917. Free PDF download.