All articles A–Z

Electromagnetism

Electromagnetism, also called electricity and magnetism, is the branch of physics treating electric and magnetic phenomena as one field, unified by James Clerk Maxwell's equations of 1865 and underlying technologies from radio and Wi-Fi to lasers.

Electromechanical wave imaging

Electromechanical wave imaging (EWI) is a noninvasive, non-ionizing ultrasound method using frame rates up to 2000 per second to map the heart's contraction sequence and localize arrhythmias.

Electromechanics

Electromechanics, also called electromechanical engineering, is the branch of engineering concerned with converting energy between electrical and mechanical forms, chiefly in motors, generators, transformers, sensors, and actuators.

Electromembrane extraction

Electromembrane extraction (EME) is a liquid-phase microextraction technique, first published in 2006, in which a dc electric field drives charged analytes across a supported liquid membrane for sample preparation.

Electromigration

Electromigration is the current-driven transport of metal atoms in a conductor: moving electrons push metal ions toward the anode, forming voids that open chip interconnects and limit integrated-circuit lifetime.

Electromotive force

Electromotive force, or emf, is the energy supplied per unit charge by a source like a battery, generator, or solar cell, measured in volts despite its misleading name.

Electromyography

Electromyography (EMG), an electrodiagnostic test recording muscle electrical activity at rest and during contraction, usually paired with nerve conduction studies to diagnose nerve and muscle disorders such as carpal tunnel syndrome and ALS.

Electron

The electron, also called the beta minus particle, is a stable, negatively charged elementary particle, the first to be discovered, by J. J. Thomson in 1897.

Electron affinity

Electron affinity (EA), also called electron gain enthalpy, is the energy released when a neutral gas-phase atom or molecule attaches an electron; chlorine has the most negative value.

Electron attachment

Electron attachment is the capture of a low-energy electron by an atom or molecule to form a negative ion, proceeding nondissociatively to a parent anion or dissociatively to fragment anions.

Electron backscatter diffraction

Electron backscatter diffraction (EBSD), also known as orientation imaging microscopy or backscatter Kikuchi diffraction, is a scanning electron microscope technique that maps crystal orientation, phase, and defects in a tilted, polished sample.

Electron beam curing

Electron beam curing (EB curing) is a nonthermal, out-of-autoclave manufacturing method that uses high-energy electrons to solidify polymer composites, coatings, and inks in seconds rather than hours.

Electron beam ion trap

An electron beam ion trap (EBIT) is a table-top device that creates and studies highly charged ions with a compressed electron beam, first built at Lawrence Livermore.

Electron beam physical vapor deposition

Electron beam physical vapor deposition (EB-PVD) is a vacuum coating technique in which an electron beam evaporates source material that condenses as a thin film on a substrate.

Electron beam therapy

Electron beam therapy, also called electron therapy, is external beam radiation therapy using high-energy electrons to treat skin and superficial tumors while sparing deeper tissues.

Electron beam-induced current

Electron beam-induced current (EBIC) is a scanning electron microscopy technique that maps the current generated when an electron beam creates electron-hole pairs in a semiconductor, revealing junctions and defects.

Electron capture

Electron capture, also called K-capture or inverse beta decay, is a radioactive decay mode in which a nucleus absorbs an inner-shell electron, converting a proton into a neutron.

Electron capture detector

The electron capture detector (ECD) is a gas chromatography detector that measures halogenated compounds at picogram levels, invented by James Lovelock and reported in 1960.

Electron capture dissociation

Electron capture dissociation (ECD) is a tandem mass spectrometry fragmentation technique, introduced in 1998, in which protein ions capture low-energy electrons and fragment along the backbone.

Electron channeling contrast imaging

Electron channeling contrast imaging, or ECCI, is a scanning electron microscopy technique that images defects such as dislocations and stacking faults in bulk samples with little preparation.

Electron configuration

Electron configuration, also called electron shell configuration, is the distribution of an atom's electrons among orbitals according to the Pauli principle, written in notation such as [Ne] 3s² 3p⁴.

Electron configurations of the elements (data page)

A data page tabulating the ground-state electron configurations and first ionization energies of the chemical elements, hydrogen through uranium, compiled by NIST and noting exceptions like chromium and copper to the simple filling order.

Electron cooling

Electron cooling is a beam-cooling technique proposed by Gersh Budker in 1966, reducing the size and energy spread of stored particle beams with a matched electron beam.

Electron counting

Electron counting is a detection mode in electron microscopy in which the camera registers each individual electron, removing readout noise and improving dose efficiency for cryo-EM.

Electron crystallography

Electron crystallography determines the atomic structure of crystals by diffracting an electron beam, working on crystals far smaller than X-ray diffraction requires and revealing light-atom positions and charge states.

Electron cyclotron current drive

Electron cyclotron current drive (ECCD) drives non-inductive current in fusion plasmas by injecting millimeter waves, providing highly localized current for tokamak operation and tearing-mode control.

Electron cyclotron resonance

Electron cyclotron resonance (ECR) is the condition in which electrons gyrating in a magnetic field absorb energy continuously from an electromagnetic wave of matching frequency.

Electron cyclotron resonance heating

Electron cyclotron resonance heating (ECRH) heats fusion plasma with microwaves tuned to the electron gyration frequency; it is the predominant heating method of the Wendelstein 7-X stellarator.

Electron deficiency

Electron deficiency in chemistry is the condition of a molecule with too few valence electrons for normal two-center two-electron bonds, so bonding is multicenter, as in diborane and the boranes.