The electron is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron's mass is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant, ħ. Being fermions, no two electrons can occupy the same quantum state, per the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: They can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavelength for a given energy.
Photoemission spectroscopy (PES), also known as photoelectron spectroscopy, refers to energy measurement of electrons emitted from solids, gases or liquids by the photoelectric effect, in order to determine the binding energies of electrons in the substance. The term refers to various techniques, depending on whether the ionization energy is provided by X-ray, XUV or UV photons. Regardless of the incident photon beam, however, all photoelectron spectroscopy revolves around the general theme of surface analysis by measuring the ejected electrons.
The Schwinger effect is a predicted physical phenomenon whereby matter is created by a strong electric field. It is also referred to as the Sauter–Schwinger effect, Schwinger mechanism, or Schwinger pair production. It is a prediction of quantum electrodynamics (QED) in which electron–positron pairs are spontaneously created in the presence of an electric field, thereby causing the decay of the electric field. The effect was originally proposed by Fritz Sauter in 1931 and further important work was carried out by Werner Heisenberg and Hans Heinrich Euler in 1936, though it was not until 1951 that Julian Schwinger gave a complete theoretical description.
Discovered only as recently as 2006 by C.D. Stanciu and F. Hansteen and published in Physical Review Letters, this effect is generally called all-optical magnetization reversal. This magnetization reversal technique refers to a method of reversing magnetization in a magnet simply by circularly polarized light and where the magnetization direction is controlled by the light helicity. In particular, the direction of the angular momentum of the photons would set the magnetization direction without the need of an external magnetic field. In fact, this process could be seen as similar to magnetization reversal by spin injection. The only difference is that now, the angular momentum is supplied by the circularly polarized photons instead of the polarized electrons.
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 also holds academic positions at Texas A&M University and the University of New Mexico. Corkum is both a theorist and an experimentalist.
Photoelectrochemical processes are processes in photoelectrochemistry; they usually involve transforming light into other forms of energy. These processes apply to photochemistry, optically pumped lasers, sensitized solar cells, luminescence, and photochromism.
In atomic, molecular, and optical physics, above-threshold ionization (ATI) is a multi-photon effect where an atom is ionized with more than the energetically required number of photons. It was first observed in 1979 by Pierre Agostini and colleagues in xenon gas.
In quantum electrodynamics (QED), the Schwinger limit is a scale above which the electromagnetic field is expected to become nonlinear. The limit was first derived in one of QED's earliest theoretical successes by Fritz Sauter in 1931 and discussed further by Werner Heisenberg and his student Hans Heinrich Euler. The limit, however, is commonly named in the literature for Julian Schwinger, who derived the leading nonlinear corrections to the fields and calculated the rate of electron–positron pair production in a strong electric field. The limit is typically reported as a maximum electric field or magnetic field before nonlinearity for the vacuum of
Double ionization is a process of formation of doubly charged ions when laser radiation is exerted on neutral atoms or molecules. Double ionization is usually less probable than single-electron ionization. Two types of double ionization are distinguished: sequential and non-sequential.
Terahertz spectroscopy detects and controls properties of matter with electromagnetic fields that are in the frequency range between a few hundred gigahertz and several terahertz. In many-body systems, several of the relevant states have an energy difference that matches with the energy of a THz photon. Therefore, THz spectroscopy provides a particularly powerful method in resolving and controlling individual transitions between different many-body states. By doing this, one gains new insights about many-body quantum kinetics and how that can be utilized in developing new technologies that are optimized up to the elementary quantum level.
Philip H. Bucksbaum is an American atomic physicist, the Marguerite Blake Wilbur Professor in Natural Science in the Departments of Physics, Applied Physics, and Photon Science at Stanford University and the SLAC National Accelerator Laboratory. He also directs the Stanford PULSE Institute.
Nam Chang-hee is a South Korean plasma physicist. Nam is specializing in the exploration of relativistic laser-matter interactions using femtosecond PW lasers. Currently he is professor of physics at Gwangju Institute of Science and Technology and director of the Center for Relativistic Laser Science as a part of the Institute for Basic Science (IBS).
The Breit–Wheeler process or Breit–Wheeler pair production is a proposed physical process in which a positron–electron pair is created from the collision of two photons. It is the simplest mechanism by which pure light can be potentially transformed into matter. The process can take the form γ γ′ → e+ e− where γ and γ′ are two light quanta.
Collaborative Computational Project Q (CCPQ) was developed in order to provide software which uses theoretical techniques to catalogue collisions between electrons, positrons or photons and atomic/molecular targets. The 'Q' stands for quantum dynamics. This project is accessible via the CCPForge website, which contains numerous other projects such as CCP2 and CCP4. The scope has increased to include atoms and molecules in strong laser fields, low-energy interactions of antihydrogen with small atoms and molecules, cold atoms, Bose–Einstein condensates and optical lattices. CCPQ gives essential information on the reactivity of various molecules, and contains two community codes R-matrix suite and MCTDH wavepacket dynamics.
Helen H. Fielding is a Professor of physical chemistry at University College London (UCL). She focuses on ultrafast transient spectroscopy of protein chromophores and molecules. She was the first woman to win the Royal Society of Chemistry (RSC) Harrison-Meldola Memorial Prize (1996) and Marlow Award (2001).
John Holmes Malmberg was an American plasma physicist and a professor at the University of California, San Diego. He was known for making the first experimental measurements of Landau damping of plasma waves in 1964, as well as for his research on non-neutral plasmas and the development of the Penning–Malmberg trap.
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.
Fabrizio Carbone is an Italian and Swiss physicist and currently an Associate Professor at École Polytechnique Fédérale de Lausanne (EPFL). His research focuses on the study of matter in out of equilibrium conditions using ultrafast spectroscopy, diffraction and imaging techniques. In 2015, he attracted international attention by publishing a photography of light displaying both its quantum and classical nature.
Jabez Jenkins McClelland is an American physicist. He is best known for his work applying the techniques of laser cooling and atom optics to nanotechnology. This work involved expanding the number of atomic species that could be laser cooled from the alkalis and a few alkaline earth and noble gas species, to transition metals such a chromium and rare earths such as erbium. In the early 1990s he and colleagues showed that the nodes of an optical standing wave could act as lenses, focusing chromium atoms as they deposit onto a surface to create a permanent grating structure whose periodicity is precisely tied to an atomic resonance frequency, making it a useful nanoscale length standard. In the early 2000s his team showed that laser cooled atoms can produce a very high brightness ion beam when ionized just above threshold, and used this technique to realize a high resolution lithium ion microscope.
A plasma mirror is an optical mechanism which can be used to specularly reflect high intensity ultrafast laser beams where nonlinear optical effects prevent the usage of conventional mirrors and to improve laser temporal contrast. If a sufficient intensity is reached, a laser beam incident on a substrate will cause the substrate to ionize and the resulting plasma will reflect the incoming beam with the qualities of an ordinary mirror. A single plasma mirror can be used only one time, as during the interaction the beam ionizes the substrate and destroys it.
