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Double Ionization
Double ionization is a process of formation of doubly charged ions when laser radiation or charged particles like electrons, positrons or heavy ions are 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. Sequential double ionization Sequential double ionization is a process of formation of doubly charged ions consisting of two single-electron ionization events: the first electron is removed from a neutral atom/molecule (leaving a singly charged ion in the ground state or an excited state) followed by detachment of the second electron from the ion. , chapter 8. Non-sequential double ionization Non-sequential double ionization is a process whose mechanism differs (in any detail) from the sequential one. For example, both the electrons leave the system simultaneously (as in alkaline earth atoms, see below), the second electron's liberatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Ionization
Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive Electric charge, 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, electrons, positrons, protons, antiprotons, 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. Uses Everyday examples of gas ionization occur within a fluorescent lamp or other electrical discharge lamps. It is also used in radiation detectors such as the Geiger- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Atomic Units
The atomic units are a system of natural units of measurement that is especially convenient for calculations in atomic physics and related scientific fields, such as computational chemistry and atomic spectroscopy. They were originally suggested and named by the physicist Douglas Hartree. Atomic units are often abbreviated "a.u." or "au", not to be confused with similar abbreviations used for astronomical units, arbitrary units, and absorbance units in other contexts. Motivation In the context of atomic physics, using the atomic units system can be a convenient shortcut, eliminating symbols and numbers and reducing the order of magnitude of most numbers involved. For example, the Hamiltonian operator in the Schrödinger equation for the helium atom with standard quantities, such as when using SI units, is : \hat = - \frac \nabla_1^2 - \frac \nabla_2^2 - \frac - \frac + \frac , but adopting the convention associated with atomic units that transforms quantities into dimensionl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Atomic, Molecular, And Optical Physics
Atomic, molecular, and optical physics (AMO) is the study of matter–matter and light–matter interactions, at the scale of one or a few atoms and energy scales around several electron volts. The three areas are closely interrelated. AMO theory includes classical, semi-classical and quantum treatments. Typically, the theory and applications of emission, absorption, scattering of electromagnetic radiation (light) from Excited state, excited atoms and molecules, analysis of spectroscopy, generation of lasers and masers, and the optical properties of matter in general, fall into these categories. Atomic and molecular physics Atomic physics is the subfield of AMO that studies atoms as an isolated system of electrons and an atomic nuclei, atomic nucleus, while molecular physics is the study of the physical properties of molecules. The term ''atomic physics'' is often associated with nuclear power and nuclear bombs, due to the synonymous use of ''atomic'' and ''nuclear'' i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Above Threshold Ionization
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. Photoelectrons In the case of ATI the photoelectron peaks should appear at : E_s = (n + s) \hbar \omega - W, where the integer ''n'' represents the minimal number of photons absorbed, and the integer ''s'' represents the number of additional photons absorbed. ''W'' is the ionization energy, and E_s is the electron kinetic energy of the peak corresponding to ''s'' additional photons being absorbed. Structure It typically has a strong maximum at the minimal number of photons to ionize the system, with successive peaks (known as ATI peaks) separated by the photon energy and thus corresponding to higher numbers of photons being absorbed. In the non-perturbative regime the bound states are dressed with the electric f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Photoionization
Photoionization is the physical process in which an ion is formed from the interaction of a photon with an atom or molecule. Cross section Not every interaction between a photon and an atom, or molecule, will result in photoionization. The probability of photoionization is related to the photoionization cross section of the species – the probability of an ionization event conceptualized as a hypothetical cross-sectional area. This cross section depends on the energy of the photon (proportional to its wavenumber) and the species being considered i.e. it depends on the structure of the molecular species. In the case of molecules, the photoionization cross-section can be estimated by examination of Franck-Condon factors between a ground-state molecule and the target ion. This can be initialized by computing the vibrations of a molecule and associated cation (post ionization) using quantum chemical software e.g. QChem. For photon energies below the ionization threshold, the photoi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Nonlinear Optics
Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in Nonlinearity, nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (when the electric field of the light is >108 V/m and thus comparable to the atomic electric field of ~1011 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear. In nonlinear optics, the superposition principle no longer holds. History The first nonlinear optical effect to be predicted was two-photon absorption, by Maria Goeppert Mayer for her PhD in 1931, but it remained an unexplored theoretical curiosity until 1961 and the almost simultaneous observation of two-photon absorption at Bell Labs and the discovery of second-harmonic generation by Peter Franken ''et al.'' at University of Michigan, both shortly after th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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List Of Laser Articles
This is a list of laser topics. A * 3D printing, additive manufacturing * Abnormal reflection * Above-threshold ionization * Absorption spectroscopy * Accelerator physics * Acoustic microscopy * Acousto-optic deflector * Acousto-optic modulator * Acousto-optical spectrometer * Acousto-optics * Active laser medium * Active optics * Advanced Precision Kill Weapon System * Advanced Tactical Laser * Afocal system * Airborne laser * Airborne wind turbine * Airy beam * ALKA * All gas-phase iodine laser * Ambient ionization * Amplified spontaneous emission * Analytical chemistry * Aneutronic fusion * Antiproton Decelerator * Apache Arrowhead * Apache Point Observatory Lunar Laser-ranging Operation * Arago spot * Argon fluoride laser * Argus laser * Asterix IV laser * Astrophysical maser * Atmospheric-pressure laser ionization * Atom interferometer * Atom laser * Atom probe * Atomic clock * Atomic coherence * Atomic fountain * Atomic line filter * Ato ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Ponderomotive Energy
In strong-field laser physics, ponderomotive energy is the cycle-averaged quiver energy of a free electron in an electromagnetic field. Equation The ponderomotive energy is given by :U_p = , where e is the electron charge, E is the linearly polarised electric field amplitude, \omega_0 is the laser carrier frequency and m is the electron mass. In terms of the laser intensity I, using I=c\epsilon_0 E^2/2, it reads less simply: :U_p \cdot , where \epsilon_0 is the vacuum permittivity. For typical orders of magnitudes involved in laser physics, this becomes: : U_p (\mathrm) = 9.33 \cdot I(10^\ \mathrm^2) \cdot \lambda^2(\mathrm^2) , where the laser wavelength is \lambda= 2\pi c/\omega_0, and c is the speed of light. The units are electronvolts (eV), watts (W), centimeters (cm) and micrometers (μm). Atomic units In atomic units, e=m=1, \epsilon_0=1/4\pi, \alpha c=1 where \alpha \approx 1/137. If one uses the atomic unit of electric field,CODATA Valueatomic unit of electric fie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Ground State
The ground state of a quantum-mechanical system is its stationary state of lowest energy; the energy of the ground state is known as the zero-point energy of the system. An excited state is any state with energy greater than the ground state. In quantum field theory, the ground state is usually called the vacuum. If more than one ground state exists, they are said to be degenerate. Many systems have degenerate ground states. Degeneracy occurs whenever there exists a unitary operator that acts non-trivially on a ground state and commutes with the Hamiltonian of the system. According to the third law of thermodynamics, a system at absolute zero temperature exists in its ground state; thus, its entropy is determined by the degeneracy of the ground state. Many systems, such as a perfect crystal lattice, have a unique ground state and therefore have zero entropy at absolute zero. It is also possible for the highest excited state to have absolute zero temperature for sys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Anne L'Huillier
Anne Geneviève L'Huillier (; born 16 August 1958) is a French physicist. She is a professor of atomic physics at Lund University in Sweden. She leads an attosecond physics group which studies the movements of electrons in real time, which is used to understand chemical reactions on the atomic level. Her experimental and theoretical research are credited with laying the foundation for the field of attochemistry. In 2003 she and her group beat the world record for the shortest laser pulse, of 170 attoseconds. L'Huillier became a member of the Royal Swedish Academy of Sciences in 2004. She has received various physics awards including the Wolf Prize in Physics in 2022 and the Nobel Prize in Physics in 2023. Life Education Anne L'Huillier was born in Paris in 1958. She was awarded a double master's degree in theoretical physics and mathematics, but switched for her doctorate degree to experimental physics at Pierre and Marie Curie University. Her dissertation was on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |