Coulombic explosions are a mechanism for transforming energy in intense electromagnetic fields into atomic motion and are thus useful for controlled destruction of relatively robust molecules. The explosions are a prominent technique in laser-based machining, and appear naturally in certain high-energy reactions.
The Coulombic repulsion of particles having the same electric charge can break the bonds that hold solids together. When done with a narrow laser beam, a small amount of solid explodes into a plasma of ionized atomic particles. It may be shown that the Coulomb explosion occurs in the same critical parameter regime as the superradiant phase transition i.e. when the destabilizing interactions become overwhelming and dominate over the native oscillatory phonon solid cluster binding motions which is also characteristic for the diamond synthesis.
With their low mass, outer valence electrons responsible for chemical bonding are easily stripped from atoms, leaving them positively charged. Given a mutually repulsive state between atoms whose chemical bonds are broken, the material explodes into a small plasma cloud of energetic ions with higher velocities than seen in thermal emission.
A Coulomb explosion is a "cold" alternative to the dominant laser etching technique of thermal ablation, which depends on local heating, melting, and vaporization of molecules and atoms using less-intense beams. Pulse brevity down only to the nanosecond regime is sufficient to localize thermal ablation – before the heat is conducted far, the energy input (pulse) has ended. Nevertheless, thermally ablated materials may seal pores important in catalysis or battery operation, and recrystallize or even burn the substrate, thus changing the physical and chemical properties at the etch site. In contrast, even light foams remain unsealed after ablation by Coulomb explosion.
Coulomb explosions for industrial machining are made with ultra-short (picosecond or femtoseconds) laser pulses. The enormous beam intensities required (10–400 terawatt per square centimeter thresholds, depending on material) are only practical to generate, shape, and deliver for very brief instants of time. Coulomb explosion etching can be used in any material to bore holes, remove surface layers, and texture and microstructure surfaces; e.g., to control ink loading in printing presses.
During a nuclear explosion based on the fission of uranium, 167 MeV is emitted in the form of a coulombic explosion between each prior nucleus of uranium, the repulsive electrostatic energy between the two fission daughter nuclei, translates into the kinetic energy of the fission products that results in both the primary driver of the blackbody radiation that rapidly generates the hot dense plasma/nuclear fireball formation and thus also both later blast and thermal effects.
At least one scientific paper suggests that coulomb explosion (specifically, the electrostatic repulsion of dissociated carboxyl groups of polyglutamic acid) may be part of the explosive action of nematocytes, the stinging cells in aquatic organisms of the phylum Cnidaria.
approximately 82% of the fission energy is released as kinetic energy of the two large fission fragments. These fragments, being massive and highly charged particles, interact readily with matter. They transfer their energy quickly to the surrounding weapon materials, which rapidly become heated
The various energies emitted per fission event pg 4. "167 MeV" is emitted by means of the repulsive electrostatic energy between the 2 daughter nuclei, which takes the form of the "kinetic energy" of the fission products, this kinetic energy results in both later blast and thermal effects. "5 MeV" is released in prompt or initial gamma radiation, "5 MeV" in prompt neutron radiation (99.36% of total), "7 MeV" in delayed neutron energy (0.64%) and "13 MeV" in beta decay and gamma decay(residual radiation)
An absolute configuration refers to the spatial arrangement of the atoms of a chiral molecular entity (or group) and its stereochemical description e.g. R or S, referring to Rectus, or Sinister, respectively.
Absolute configurations for a chiral molecule (in pure form) are most often obtained by X-ray crystallography. All enantiomerically pure chiral molecules crystallise in one of the 65 Sohncke groups (chiral space groups).
Alternative techniques are optical rotatory dispersion, vibrational circular dichroism, use of chiral shift reagents in proton NMR and Coulomb explosion imaging.When the absolute configuration is obtained the assignment of R or S is based on the Cahn–Ingold–Prelog priority rules.
Absolute configurations are also relevant to characterization of crystals.
Until 1951 it was not possible to obtain the absolute configuration of chiral compounds. It was at some time decided that (+)-glyceraldehyde was the (R)-enantiomer. The configuration of other chiral compounds was then related to that of (+)-glyceraldehyde by sequences of chemical reactions. For example, oxidation of (+)-glyceraldehyde (1) with mercury oxide gives (−)-glyceric acid (2), a reaction that does not alter the stereocenter. Thus the absolute configuration of (−)-glyceric acid must be the same as that of (+)-glyceraldehyde. Nitric acid oxidation of (+)-isoserine (3) gives (–)-glyceric acid, establishing that (+)-isoserine also has the same absolute configuration. (+)-Isoserine can be converted by a two-stage process of bromination and zinc reduction to give (–)-lactic acid, therefore (–)-lactic acid also has the same absolute configuration. If a reaction gave the enantiomer of a known configuration, as indicated by the opposite sign of optical rotation, it would indicate that the absolute configuration is inverted.
In 1951 Johannes Martin Bijvoet for the first time used in X-ray crystallography the effect of anomalous dispersion, which is now referred to as resonant scattering, to determine absolute configuration. The compound investigated was (+)-sodium rubidium tartrate and from its configuration (R,R) it was deduced that the original guess for (+)-glyceraldehyde was correct.Alkali metal
The alkali metals are a group (column) in the periodic table consisting of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). This group lies in the s-block of the periodic table of elements as all alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties. Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour.
The alkali metals are all shiny, soft, highly reactive metals at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1. They can all be cut easily with a knife due to their softness, exposing a shiny surface that tarnishes rapidly in air due to oxidation by atmospheric moisture and oxygen (and in the case of lithium, nitrogen). Because of their high reactivity, they must be stored under oil to prevent reaction with air, and are found naturally only in salts and never as the free elements. Caesium, the fifth alkali metal, is the most reactive of all the metals. In the modern IUPAC nomenclature, the alkali metals comprise the group 1 elements, excluding hydrogen (H), which is nominally a group 1 element but not normally considered to be an alkali metal as it rarely exhibits behaviour comparable to that of the alkali metals. All the alkali metals react with water, with the heavier alkali metals reacting more vigorously than the lighter ones.
All of the discovered alkali metals occur in nature as their compounds: in order of abundance, sodium is the most abundant, followed by potassium, lithium, rubidium, caesium, and finally francium, which is very rare due to its extremely high radioactivity; francium occurs only in the minutest traces in nature as an intermediate step in some obscure side branches of the natural decay chains. Experiments have been conducted to attempt the synthesis of ununennium (Uue), which is likely to be the next member of the group, but they have all met with failure. However, ununennium may not be an alkali metal due to relativistic effects, which are predicted to have a large influence on the chemical properties of superheavy elements; even if it does turn out to be an alkali metal, it is predicted to have some differences in physical and chemical properties from its lighter homologues.
Most alkali metals have many different applications. One of the best-known applications of the pure elements is the use of rubidium and caesium in atomic clocks, of which caesium atomic clocks are the most accurate and precise representation of time. A common application of the compounds of sodium is the sodium-vapour lamp, which emits light very efficiently. Table salt, or sodium chloride, has been used since antiquity. Lithium finds use as a psychiatric medication. Sodium and potassium are also essential elements, having major biological roles as electrolytes, and although the other alkali metals are not essential, they also have various effects on the body, both beneficial and harmful.Bromochlorofluoromethane
Bromochlorofluoromethane or fluorochlorobromomethane, is a chemical compound and trihalomethane deriative with the chemical formula CHBrClF. As one of the simplest possible stable chiral compounds, it is useful for fundamental research into this area of chemistry. However its relative instability to hydrolysis, and lack of suitable functional groups, made separation of the enantiomers of bromochlorofluoromethane especially challenging, and this was not accomplished until almost a century after it was first synthesised, in March 2005, though it has now been done by a variety of methods. More recent research using bromochlorofluoromethane has focused on its potential use for experimental measurement of parity violation, a major unsolved problem in quantum physics.Collision cascade
A collision cascade (also known as a displacement cascade or a displacement spike) is a set of nearby adjacent energetic (much higher than ordinary thermal energies) collisions of atoms induced by an energetic particle in a solid or liquid.If the maximum atom or ion energies in a collision cascade are higher than the threshold displacement energy of the material (tens of eVs or more), the collisions can permanently displace atoms from their lattice sites and produce defects. The initial energetic atom can be, e.g., an ion from a particle accelerator, an atomic recoil produced by a passing high-energy neutron, electron or photon, or be produced when a radioactive nucleus decays and gives the atom a recoil energy.
The nature of collision cascades can vary strongly depending on the energy and mass of the recoil/incoming ion and density of the material (stopping power).Electron beam ion trap
Electron beam ion trap (EBIT) is an electromagnetic bottle that produces and confines highly charged ions. An EBIT uses an electron beam focused with a powerful magnetic field to ionize atoms to high charge states by successive electron impact.
It was invented by M. Levine and R. Marrs at LLNL and LBNL.Electron wake
Electron wake is the disturbance left after a high-energy charged particle passes
through condensed matter or plasma. Ions passing through can introduce periodic oscillations in the crystal lattice or plasma wave with the characteristic frequency of the crystal or plasma frequency. Interactions of the field created by these oscillations with the charged particle field alternate from constructive interference to destructive interference, producing alternating waves of electric field and displacement. The frequency of the wake field is determined by the nature of the penetrated matter, and the period of the wake field is directly proportional to the speed of the incoming charged particle. The amplitude of the first wake wave is the most important, as it produces a braking force on the charged particle, eventually slowing it down. Wake fields also can capture and guide lightweight ions or positrons in the direction perpendicular to the wake. The larger the speed of the original charged particle, the larger the angle between the initial particle's velocity and the captured ion's velocity.Helium trimer
The helium trimer is a weakly bound molecule consisting of three helium atoms. Van der Waals forces link the atoms together. The combination of three atoms is much more stable than the two atom helium dimer. The three atom combination of helium-4 atoms is an Efimov state. Helium-3 is predicted to form a trimer, although ground state dimers containing helium-3 are completely unstable.Helium trimer molecules have been produced by expanding cold helium gas from a nozzle into a vacuum chamber. Such a set up also produces the helium dimer and other helium atom clusters. The existence of the molecule was proven by matter wave diffraction on a diffraction grating. The kind of grating used needs to have empty space between the bars, so that molecules can pass through, glass would stop helium. Properties of the molecules can be discovered by Coulomb explosion imaging in which a laser ionizes all three atoms simultaneously, and then three ions fly apart and are then detected.
The helium trimer is large, being more than 100 Å, which is even larger than the helium dimer. The atoms are not arranged in an equilateral triangle as might be expected, but form random shaped triangles.Interatomic Coulombic decay can occur when one atom is ionised and excited. It can transfer energy to another atom in the trimer, even though they are separated. However this is much more likely to occur when the atoms are close together, and so the interatomic distances measured by this vary with half full height from 3.3 to 12 Å. The predicted mean distance for Interatomic Coulombic decay in 4He3 is 10.4 Å. For 3He4He2 this distance is even larger at 20.5 Å.High-speed camera
A high-speed camera is a device capable of capturing moving images with exposures of less than 1/1,000 second or frame rates in excess of 250 frames per second. It is used for recording fast-moving objects as photographic images onto a storage medium. After recording, the images stored on the medium can be played back in slow motion. Early high-speed cameras used film to record the high-speed events, but were superseded by entirely electronic devices using either a charge-coupled device (CCD) or a CMOS active pixel sensor, recording, typically, over 1,000 frames per second onto DRAM, to be played back slowly to study the motion for scientific study of transient phenomena.Interatomic Coulombic decay
Interatomic Coulombic decay (ICD) is a general, fundamental property of atoms and molecules which have neighbors. Interatomic (intermolecular) Coulombic decay is a very efficient interatomic (intermolecular) relaxation process of an electronically excited atom or molecule embedded in an environment. Without the environment the process cannot take place. Until now it has been mainly demonstrated for atomic and molecular clusters, independently of whether they are of van-der-Waals or hydrogen bonded type.
The nature of the process can be depicted as follows: Consider a cluster with two subunits, A and B. Suppose an inner-valence electron is removed from subunit A. If the resulting (ionized) state is higher in energy than the double ionization threshold of subunit A then an intraatomic (intramolecular) process (autoionization, in the case of core ionization Auger decay) sets in. Even though the excitation is energetically not higher than the double ionization threshold of subunit A itself, it may be higher than the double ionization threshold of the cluster which is lowered due to charge separation. If this is the case, an interatomic (intermolecular) process sets in which is called ICD. During the ICD the excess energy of subunit A is used to remove (due to electronic correlation) an outer-valence electron from subunit B. As a result, a doubly ionized cluster is formed with a single positive charge on A and B. Thus, charge separation in the final state is a fingerprint of ICD. As a consequence of the charge separation the cluster typically breaks apart via Coulomb explosion.
ICD is characterized by its decay rate or the lifetime of the excited state. The decay rate depends on the interatomic (intermolecular) distance of A and B and its dependence allows to draw conclusions on the mechanism of ICD. Particularly important is the determination of the kinetic energy spectrum of the electron emitted from subunit B which is denoted as ICD electron. ICD electrons are often measured in ICD experiments. Typically, ICD takes place on the femto second time scale, many orders of magnitude faster than those of the competing photon emission and other relaxation processes.List of plasma physics articles
This is a list of plasma physics topics.List of things named after Charles-Augustin de Coulomb
A list of things named for French physicist Charles-Augustin de Coulomb (1736–1806). For additional uses of the term, see coulomb (disambiguation)
coulomb (symbol C), the SI unit of electric charge
Coulomb-metre, alternate term for the Debye
Coulomb scattering (Rutherford scattering)
Coulomb scattering state
Coulomb stress transfer
Coulomb wave function
A coulomb wave function is a solution to the coulomb wave equation
Coulomb, a lunar crater
Coulomb-Sarton Basin, lunar basin named after the craters Coulomb and Sarton
Interatomic Coulombic decay
Screened Coulomb Potentials Implicit Solvent Model
Statcoulomb (Symbol statC)Neon compounds
Neon compounds were long believed not to exist. Neutral neon-containing molecules were only discovered in the twenty-first century, and even today are not well known. Neon is a noble gas with a high first ionisation potential of 21.564 eV, which is only exceeded by that of helium (24.587 eV). This means that ionic compounds use too much energy to make. Neon's polarisability of 0.395 Å3 is the second lowest of any element (only helium's is more extreme). Low polarisability means there will be little tendency to stick to other atoms. Neon has a Lewis basicity or proton affinity of 2.06 eV. However, there are molecular ions which contain neon, as well as temporary excited neon-containing molecules called excimers. Several neutral neon molecules have been predicted to be stable, but have not yet been found to exist. Neon has been shown to crystallise with other substances to form clathrates or Van der Waals solids.Neutron bomb
A neutron bomb, officially defined as a type of enhanced radiation weapon (ERW), is a low yield thermonuclear weapon designed to maximize lethal neutron radiation in the immediate vicinity of the blast while minimizing the physical power of the blast itself. The neutron release generated by a nuclear fusion reaction is intentionally allowed to escape the weapon, rather than being absorbed by its other components. The neutron burst, which is used as the primary destructive action of the warhead, is able to penetrate enemy armor more effectively than a conventional warhead, thus making it more lethal as a tactical weapon.
The concept was originally developed by the US in the late 1950s and early 1960s. It was seen as a "cleaner" bomb for use against massed Soviet armored divisions. As these would be used over allied nations, notably West Germany, the reduced blast damage was seen as an important advantage.ERWs were first operationally deployed for anti-ballistic missiles (ABM). In this role the burst of neutrons would cause nearby warheads to undergo partial fission, preventing them from exploding properly. For this to work, the ABM would have to explode within ca. 100 metres (300 ft) of its target. The first example of such a system was the W66, used on the Sprint missile used in the US's Nike-X system. It is believed the Soviet equivalent, the A-135's 53T6 missile, uses a similar design.The weapon was once again proposed for tactical use by the US in the 1970s and 1980s, and production of the W70 began for the MGM-52 Lance in 1981. This time it experienced a firestorm of protest as the growing anti-nuclear movement gained strength through this period. Opposition was so intense that European leaders refused to accept it on their territory. President Ronald Reagan bowed to pressure and the built examples of the W70-3 remained stockpiled in the US until they were retired in 1992. The last W70 was dismantled in 2011.Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller nuclei(lighter nuclei). The fission process often produces free neutrons and gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay.
Nuclear fission of heavy elements was discovered on December 17, 1938 by German Otto Hahn and his assistant Fritz Strassmann, and explained theoretically in January 1939 by Lise Meitner and her nephew Otto Robert Frisch. Frisch named the process by analogy with biological fission of living cells. For heavy nuclides, it is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments (heating the bulk material where fission takes place). In order for fission to produce energy, the total binding energy of the resulting elements must be more negative (greater binding energy) than that of the starting element.
Fission is a form of nuclear transmutation because the resulting fragments are not the same element as the original atom. The two nuclei produced are most often of comparable but slightly different sizes, typically with a mass ratio of products of about 3 to 2, for common fissile isotopes. Most fissions are binary fissions (producing two charged fragments), but occasionally (2 to 4 times per 1000 events), three positively charged fragments are produced, in a ternary fission. The smallest of these fragments in ternary processes ranges in size from a proton to an argon nucleus.
Apart from fission induced by a neutron, harnessed and exploited by humans, a natural form of spontaneous radioactive decay (not requiring a neutron) is also referred to as fission, and occurs especially in very high-mass-number isotopes. Spontaneous fission was discovered in 1940 by Flyorov, Petrzhak and Kurchatov in Moscow, when they decided to confirm that, without bombardment by neutrons, the fission rate of uranium was indeed negligible, as predicted by Niels Bohr; it was not.The unpredictable composition of the products (which vary in a broad probabilistic and somewhat chaotic manner) distinguishes fission from purely quantum-tunneling processes such as proton emission, alpha decay, and cluster decay, which give the same products each time. Nuclear fission produces energy for nuclear power and drives the explosion of nuclear weapons. Both uses are possible because certain substances called nuclear fuels undergo fission when struck by fission neutrons, and in turn emit neutrons when they break apart. This makes a self-sustaining nuclear chain reaction possible, releasing energy at a controlled rate in a nuclear reactor or at a very rapid, uncontrolled rate in a nuclear weapon.
The amount of free energy contained in nuclear fuel is millions of times the amount of free energy contained in a similar mass of chemical fuel such as gasoline, making nuclear fission a very dense source of energy. The products of nuclear fission, however, are on average far more radioactive than the heavy elements which are normally fissioned as fuel, and remain so for significant amounts of time, giving rise to a nuclear waste problem. Concerns over nuclear waste accumulation and over the destructive potential of nuclear weapons are a counterbalance to the peaceful desire to use fission as an energy source.Pavel Jungwirth
Pavel Jungwirth (born May 20, 1966 in Prague, Czech Republic) is a Czech organic chemist. Since 2004, he has been the head of the Senior Research Group at the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences. He has also been a professor in the Faculty of Mathematics and Physics at Charles University since 2000. He has also been a senior editor of the Journal of Physical Chemistry since 2009. He is popularly known for studying the explosive reaction between alkali metals, such as sodium and potassium, and water; his research on this subject indicates that these reactions result from a Coulomb explosion. He and his colleagues have also discovered a way to slow down this reaction, which they used to determine the source of a blue flash that is briefly produced during the reaction.Phil Mason
Philip E. Mason is a British chemist and video blogger who posts YouTube videos criticizing creationism, religion, pseudoscience and feminism, under the pseudonym Thunderf00t. He works as a scientist in the fields of chemistry and biochemistry at the Institute of Organic Chemistry and Biochemistry of the Academy of Sciences of the Czech Republic.Rydberg matter
Rydberg matter is an exotic phase of matter formed by Rydberg atoms; it was predicted around 1980 by É. A. Manykin, M. I. Ozhovan and P. P. Poluéktov. It has been formed from various elements like caesium, potassium, hydrogen and nitrogen; studies have been conducted on theoretical possibilities like sodium, beryllium, magnesium and calcium. It has been suggested to be a material that diffuse interstellar bands may arise from. Circular Rydberg states, where the outermost electron is found in a planar circular orbit, are the most long-lived, with lifetimes of up to several hours, and are the most common.Swift heavy ion
Swift heavy ions are a special form of particle radiation for which electronic stopping dominates over nuclear stopping.
They are accelerated in particle accelerators to very high energies, typically in the MeV or GeV range and have sufficient energy and mass to penetrate solids on a straight line. In many solids swift heavy ions release sufficient energy to induce permanently modified cylindrical zones, so-called ion tracks. If the irradiation is carried out in an initially crystalline material, ion tracks consist of an amorphous cylinder. Ion tracks can be produced in many amorphizing materials, but not in pure metals, where the high electronic heat conductivity dissipates away the electronic heating before the ion track has time to form.Vaporization
Vaporization (or vaporisation) of an element or compound is a phase transition from the liquid phase to vapor. There are two types of vaporization: evaporation and boiling. Evaporation is a surface phenomenon, whereas boiling is a bulk phenomenon.
Evaporation is a phase transition from the liquid phase to vapor (a state of substance below critical temperature) that occurs at temperatures below the boiling temperature at a given pressure. Evaporation occurs on the surface. Evaporation only occurs when the partial pressure of vapor of a substance is less than the equilibrium vapor pressure. For example, due to constantly decreasing or negative pressures, vapor pumped out of a solution will leave behind a cryogenic liquid.
Boiling is also a phase transition from the liquid phase to gas phase, but boiling is the formation of vapor as bubbles of vapor below the surface of the liquid. Boiling occurs when the equilibrium vapor pressure of the substance is greater than or equal to the environmental pressure. The temperature at which boiling occurs is the boiling temperature, or boiling point. The boiling point varies with the pressure of the environment.
Sublimation is a direct phase transition from the solid phase to the gas phase, skipping the intermediate liquid phase. Because it does not involve the liquid phase, it is not a form of vaporization.
The term vaporization has also been used in a colloquial or hyperbolic way to refer to the physical destruction of an object that is exposed to intense heat or explosive force, where the object is actually blasted into small pieces rather than literally converted to gaseous form. Examples of this usage include the "vaporization" of the uninhabited Marshall Island of Elugelab in the 1952 Ivy Mike thermonuclear test.At the moment of a large enough meteor or comet impact, bolide detonation, a nuclear fission, thermonuclear fusion, or theoretical antimatter weapon detonation, a flux of so many gamma ray, x-ray, ultraviolet, visual light and heat photons strikes matter in a such brief amount of time (a great number of high-energy photons, many overlapping in the same physical space) that all molecules lose their atomic bonds and "fly apart". All atoms lose their electron shells and become positively charged ions, in turn emitting photons of a slightly lower energy than they had absorbed. All such matter becomes a gas of nuclei and electrons which rise into the air due to the extremely high temperature or bond to each other as they cool. The matter vaporized this way is immediately a plasma in a state of maximum entropy and this state steadily reduces via the factor of passing time due to natural processes in the biosphere and the effects of physics at normal temperatures and pressures.
A similar process occurs during ultrashort pulse Laser ablation, where the high flux of incoming electromagnetic radiation strips the target material's surface of electrons, leaving positively charged atoms which undergo a coulomb explosion.