codzienność: Scattering

Evidence: 78 • authority: 72

In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deflect from a straight trajectory or are blocked by localized non-uniformities (including particles, matter, interfaces, and radiation) in the propagation medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection. Reflections of radiation that undergo scattering are often called diffuse reflections and unscattered reflections are called specular (mirror-like) reflections. Originally, the term was confined to light scattering (going back at least as…

Evidence: 48 • authority: 72

Atoms are the basic particles of the chemical elements and the fundamental building blocks of matter. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium, and any atom that contains 29 protons is copper. Atoms with the same number of protons but a different number of neutrons are called isotopes of the same element. Atoms are extremely small, typically around 100 picometers across. A human hair is about a million carbon atoms wide. Atoms are smaller than t…

Evidence: 48 • authority: 72

Compton scattering (or the Compton effect) is the quantum theory of scattering of a high-frequency photon through an interaction with a charged particle, usually an electron. Specifically, when the photon interacts with a loosely bound electron, it releases the electron from an outer valence shell of an atom or molecule. The effect was discovered in 1923 by Arthur Holly Compton while researching the scattering of X-rays by light elements, which earned him the Nobel Prize in Physics in 1927. The Compton effect significantly deviated from dominating classical theories, using both special relativity and quantum mechanics to explain the interaction between high frequency photons and charged par…

Evidence: 41 • authority: 72

Quantum entanglement is the phenomenon in which the quantum state of each particle in a group cannot be described independently of the state of the others, even when the particles are separated by a large distance. The topic of quantum entanglement is at the heart of the disparity between classical physics and quantum physics: entanglement is a primary feature of quantum mechanics not present in classical mechanics. Measurements of physical properties such as position, momentum, spin, and polarization performed on entangled particles can, in some cases, be found to be perfectly correlated. For example, if a pair of entangled particles is generated such that their total spin is known to be z…

Evidence: — • authority: 72

The electron (e−, or β− in nuclear reactions) is a subatomic particle whose electric charge is negative one elementary charge. It is an elementary particle contained in the matter that makes up the universe. All atoms are composed of electrons, as well as varying numbers protons and neutrons, but the electrons have almost 2,000 times less mass than the other two constituents. In atoms, an electron's matter wave occupies atomic orbitals around a positively charged atomic nucleus. The configuration and energy levels of an atom's electrons determine the atom's chemical properties. Electrons are bound to the nucleus to different degrees. The outermost or valence electrons are the least tightly…

Evidence: — • authority: 72

In chemistry and physics, Raman scattering or the Raman effect () is the inelastic scattering of photons by matter, meaning that there is both an exchange of energy (change of light frequency) and a change in the light's direction (momentum). Typically this effect involves vibrational energy being gained by a molecule as incident photons from a visible laser are shifted to lower energy. This is called normal Stokes-Raman scattering. Light has a certain probability of being scattered by a material. When photons are scattered, most of them are elastically scattered (Rayleigh scattering), such that the scattered photons have the same energy (frequency, wavelength, and therefore color) as the i…

Evidence: — • authority: 72

The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008, in collaboration with over 10,000 scientists, and hundreds of universities and laboratories across more than 100 countries. It lies in a tunnel 27 kilometres (17 mi) in circumference and as deep as 175 metres (574 ft) beneath the France–Switzerland border near Geneva. The first collisions were achieved in 2010 at an energy of 3.5 tera-electronvolts (TeV) per beam, about four times the previous world record. The discovery of the Higgs boson at the LHC was announced in 2012. Between 2013 and 2015, the LHC w…

Evidence: — • authority: 72

The Rutherford scattering experiments were a landmark series of experiments by which scientists learned that every atom has a nucleus where all of its positive charge and most of its mass is concentrated. They deduced this after measuring how an alpha particle beam is scattered when it strikes a thin metal foil. The experiments were performed between 1906 and 1913 by Hans Geiger and Ernest Marsden under the direction of Ernest Rutherford at the Physical Laboratories of the University of Manchester. The physical phenomenon was explained by Rutherford in a classic 1911 paper that eventually led to the widespread use of scattering in particle physics to study subatomic matter. Rutherford scatt…

Evidence: — • authority: 80

Interactions of Photons and Electrons with Molecules

Evidence: — • authority: 80

On the relativistic corrections to the cross-section for inelastic scattering of photons on atomic electrons

Evidence: — • authority: 88

Effect of Charged Particle-Neutral Collisions on Collective Thomson Scattering. The effect of charged particle-neutral collisions on the spectrum of electromagnetic radiation scattered by the free electrons in plasmas is investigated. The calculations are restricted to the regime where λe ≫ k−1 > λD, where λe is the mean free path for electron, k is the magnitude of the scattering k vector, and λD is the Debye length. The spectral density of the electron density fluctuations is computed from the Vlasov equation with the aid of a relaxational collision model. The results thus obtained correspond to Salpeter's expressions with a finite damping constant. The effect of collisions with neutrals…

Evidence: — • authority: 92

Mechanisms Involved in Cellulose Depolymerization by Treatment with Energetic Beams.. Depolymerized cellulose is a precursor to bioethanol, an attractive solution for the green economy. A method for cellulose depolymerization is treatment with energetic particles that break the bonds between glucose units. The scientific literature on depolymerization by energetic electrons is reviewed and analyzed. If all electron energy is spent on complete depolymerization to fermentable sugars, the theoretical dose is estimated to be about 1000 kGy. The experimental results, however, indicate rather poor energy efficiency, which is attributable to several factors. Regardless of the cellulose source, exp…