Hermann Grimmeiss is a German-Swedish physicist who focused his research on studies of the emission of electrons or other free carriers when light is shone onto a what?
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Hermann Grimmeiss Hermann Grimmeiss (August 19, 1930), is a German-Swedish physicist. He became the first professor of solid-state physics at Lund University in 1965, and he held his post until his retirement in 1996. He became an important part of the Department of Physics and focused his research on electrical and photoelectric studies of semiconductor defects. He was elected as a member of the Royal Swedish Academy of Engineering Sciences in 1977 and the Royal Swedish Academy of Sciences in 1978.
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Photoelectric effect The photoelectric effect is the emission of electrons or other free carriers when light is shone onto a material. Electrons emitted in this manner can be called "photo electrons". The phenomenon is commonly studied in electronic physics, as well as in fields of chemistry, such as quantum chemistry or electrochemistry.
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Magnetic lens A magnetic lens is a device for the focusing or deflection of moving charged particles, such as electrons or ions, by use of the magnetic Lorentz force. Its strength can often be varied by usage of electromagnets. Magnetic lenses are used in diverse applications, from cathode ray tubes over electron microscopy to particle accelerators.
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Secondary emission Secondary emission in physics is a phenomenon where primary incident particles of sufficient energy, when hitting a surface or passing through some material, induce the emission of secondary particles. The term often refers to the emission of electrons when charged particles like electrons or ions in a vacuum tube strike a metal surface; these are called secondary electrons. In this case, the number of secondary electrons emitted per incident particle is called secondary emission yield. If the secondary particles are ions, the effect is termed secondary ion emission. Secondary electron emission is used in photomultiplier tubes and image intensifier tubes to amplify the small number of photoelectrons produced by photoemission, making the tube more sensitive. It also occurs as an undesirable side effect in electronic vacuum tubes when electrons from the cathode strike the anode, and can cause parasitic oscillation.
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Critical illumination Critical illumination or Nelsonian illumination is a method of specimen illumination used for transmitted and reflected light (trans- and epi-illuminated) optical microscopy. Critical illumination focuses an image of a light source on to the specimen for bright illumination. Critical illumination generally has problems with evenness of illumination as an image of the illumination source (for example a halogen lamp filament) is visible in the resulting image. Köhler illumination has largely replaced critical illumination in modern scientific light microscopy although it requires additional optics which less expensive and simpler light microscopes may not have.
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Electron multiplier An electron multiplier is a vacuum-tube structure that multiplies incident charges. In a process called secondary emission, a single electron can, when bombarded on secondary-emissive material, induce emission of roughly 1 to 3 electrons. If an electric potential is applied between this metal plate and yet another, the emitted electrons will accelerate to the next metal plate and induce secondary emission of still more electrons. This can be repeated a number of times, resulting in a large shower of electrons all collected by a metal anode, all having been triggered by just one.
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Solvated electron A solvated electron is a free electron in (solvated in) a solution, and is the smallest possible anion. Solvated electrons occur widely, although it is difficult to observe them directly since their lifetimes are so short.The deep color of solutions of alkali metals in ammonia arises from the presence of solvated electrons: blue when dilute and copper-colored when more concentrated (> 3 molar). Classically, discussions of solvated electrons focus on their solutions in ammonia, which are stable for days, but solvated electrons occur in water and other solvents; in fact, any solvent that mediates outer-sphere electron transfer. The solvated electron is responsible for a great deal of radiation chemistry.
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Laser-induced breakdown spectroscopy Laser-induced breakdown spectroscopy (LIBS) is a type of atomic emission spectroscopy which uses a highly energetic laser pulse as the excitation source. The laser is focused to form a plasma, which atomizes and excites samples. The formation of the plasma only begins when the focused laser achieves a certain threshold for optical breakdown, which generally depends on the environment and the target material. In principle, LIBS can analyze any matter regardless of its physical state, be it solid, liquid or gas. Because all elements emit light of characteristic frequencies when excited to sufficiently high temperatures, LIBS can (in principle) detect all elements, limited only by the power of the laser as well as the sensitivity and wavelength range of the spectrograph & detector. If the constituents of a material to be analyzed are known, LIBS may be used to evaluate the relative abundance of each constituent element, or to monitor the presence of impurities. In practice, detection limits are a function of a) the plasma excitation temperature, b) the light collection window, and c) the line strength of the viewed transition. LIBS makes use of optical emission spectrometry and is to this extent very similar to arc/spark emission spectroscopy.
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Scharnhorst effect The Scharnhorst effect is a hypothetical phenomenon in which light signals travel slightly faster than "c" between two closely spaced conducting plates. It was first predicted in a 1993 paper by Klaus Scharnhorst of the Humboldt University of Berlin, Germany, and Gabriel Barton of the University of Sussex in Brighton, England. An American physicist, Timothy Retter, independently predicted the phenomenon in 2015. Scharnhorst and Barton showed using quantum electrodynamics that the effective refractive index, at low frequencies, in the space between the plates was less than 1 (which by itself does not imply superluminal signaling). They were not able to show that the wavefront velocity exceeds "c" (which would imply superluminal signaling) but argued that it is plausible.
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Luminescence Luminescence is emission of light by a substance not resulting from heat; it is thus a form of cold-body radiation. It can be caused by chemical reactions, electrical energy, subatomic motions or stress on a crystal, which all are ultimately caused by Spontaneous emission. This distinguishes luminescence from incandescence, which is light emitted by a substance as a result of heating. Historically, radioactivity was thought of as a form of "radio-luminescence", although it is today considered to be separate since it involves more than electromagnetic radiation.
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Diffuse reflection Diffuse reflection is the reflection of light or other waves or particles from a surface such that a ray incident on the surface is scattered at many angles rather than at just one angle as in the case of specular reflection. An "ideal" diffuse reflecting surface is said to exhibit Lambertian reflection, meaning that there is equal luminance when viewed from all directions lying in the half-space adjacent to the surface.
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NA61 experiment NA61/SHINE (standing for "SPS Heavy Ion and Neutrino Experiment") is a particle physics experiment at the Super Proton Synchrotron (SPS) at the European Organization for Nuclear Research (CERN). The experiment studies the hadronic final states produced in interactions of various beam particles (pions, protons and beryllium, argon, and xenon nuclei) with a variety of fixed nuclear targets at the SPS energies.
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Auger effect The Auger effect is a physical phenomenon in which the filling of an inner-shell vacancy of an atom is accompanied by the emission of an electron from the same atom. When a core electron is removed, leaving a vacancy, an electron from a higher energy level may fall into the vacancy, resulting in a release of energy. Although most often this energy is released in the form of an emitted photon, the energy can also be transferred to another electron, which is ejected from the atom; this second ejected electron is called an Auger electron. The effect was first discovered by Lise Meitner in 1922; Pierre Victor Auger independently discovered the effect shortly after and is credited with the discovery in most of the scientific community, in accordance with Stiegler's law of eponymy.
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Lambertian reflectance Lambertian reflectance is the property that defines an ideal "matte" or diffusely reflecting surface. The apparent brightness of a Lambertian surface to an observer is the same regardless of the observer's angle of view. More technically, the surface's luminance is isotropic, and the luminous intensity obeys Lambert's cosine law. Lambertian reflectance is named after Johann Heinrich Lambert, who introduced the concept of perfect diffusion in his 1760 book "Photometria".
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Electromagnetic radiation In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-, and gamma rays.
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Strahl (astronomy) Strahl, from the German for "ray" or "beam" such as radiation is, is the electron component of the solar wind that is the most closely aligned with the magnetic field of the Sun. These electrons are part of the high speed component of the solar wind and have sufficient velocity to escape from the electrostatic potential of the Sun. They carry the electron heat flux of the solar wind and always move away from the Sun along the magnetic field lines. Strahl are distinguished from the 'core' and 'halo' populations of electrons, which form part of the low and high speed solar winds and are normally anisotropic with respect to the Sun's magnetic field.
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Kramers' opacity law Kramers' opacity law describes the opacity of a medium in terms of the ambient density and temperature, assuming that the opacity is dominated by bound-free absorption (the absorption of light during ionization of a bound electron) or free-free absorption (the absorption of light when scattering a free ion, also called bremsstrahlung). It is often used to model radiative transfer, particularly in stellar atmospheres. The relation is named after the Dutch physicist Hendrik Kramers, who first derived the form in 1923.
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Digicon A digicon detector is a spatially resolved light detector using the photoelectric effect directly. It uses magnetic and electric fields operating in a vacuum to focus the electrons released from a photocathode by incoming light onto a collection of silicon diodes. It is a photon-counting instrument, so most useful for weak sources.
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Ferdinand-Braun-Institut The Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik (FBH) is a research institute, which belongs to the Forschungsverbund Berlin e. V. (FVB) and is a member of the Gottfried Wilhelm Leibniz Scientific Community. The institute is located in Berlin at the Wissenschafts- und Wirtschaftsstandort Adlershof (WISTA), its research activity is applied science in the fields of microwaves und optoelectronics.
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Electron optics Electron optics is a mathematical framework for the calculation of particle paths along given electrostatic or magnetostatic fields. The term "optics" is used because a charged particle beam can be manipulated using magnetic or electrostatic lenses in a similar fashion to the manipulation of a light beam with optical lenses.
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Liénard–Wiechert potential Liénard–Wiechert potentials describe the classical electromagnetic effect of a moving electric point charge in terms of a vector potential and a scalar potential in the Lorenz gauge. Built directly from Maxwell's equations, these potentials describe the complete, relativistically correct, time-varying electromagnetic field for a point charge in arbitrary motion, but are not corrected for quantum-mechanical effects. Electromagnetic radiation in the form of waves can be obtained from these potentials. These expressions were developed in part by Alfred-Marie Liénard in 1898 and independently by Emil Wiechert in 1900.
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Levitation Levitation (from Latin "levitas" "lightness") is the process by which an object is held aloft, without mechanical support, in a stable position.