A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Electron
Affinity
Amount of energy released when an electron is added to
element to create anion.
Electron
Diffraction
Electron
diffraction is a collective scattering phenomenon with electrons being (nearly
elastically) scattered by atoms in a regular array (crystal). This can be
understood in analogy to the Huygens principle for the diffraction of light.
The incoming plane electron wave interacts with the atoms, and secondary waves
are generated which interfere with each other. This occurs either
constructively (reinforcement at certain scattering angles generating
diffracted beams) or destructively (extinguishing of beams).
Electron
Gas
Free electrons
behavior in vacuum or metallic conductor.
Electron
Gun
Arrangement to
produce a fine beam of electrons accelerated to desired velocity.
Electron-Ion
Pair
Ionization is the
process of removing one or more electrons from a neutral atom. This results in
the loss of units of negative charge by the affected atom. The atom becomes
electrically positive (a positive ion). The products of a single ionizing event
are called an electron-ion pair.
Electron
Lens
It is a system
which uses both electric and magnetic fields to focus a beam of electrons.
Electron
Mass
Rest mass of
electron is one of the fundamental constants of Physics. It is the mass of rest
electron, the value of which is 9.11x10-31
Kg or ~ 0.51MeV/C2.
Electron
Microscope
The electron
microscope is a type of microscope that uses a beam of electrons to create an
image of the specimen. It is capable of much higher magnifications and has a
greater resolving power than an optical microscope, allowing it to see much
smaller objects in free details.
Electron
Microscopy
Technique used to
study the microstructure details of crystalline specimen. Electron microscope
is capable of obtaining higher magnification. An image of structure under
investigation is formed using beams of electrons instead of light radiation.
According to quantum mechanics, a high velocity electron will become wave like,
having a wavelength that is inversely proportional to its velocity. When
accelerated across large voltages, electrons can be made to have wavelengths on
order of 0.003nm. High magnifications and resolving powers of these microscopes
are consequences of shorter wavelengths of electron beam. The electron beam is
focused and image is formed with magnetic lens. Both transmission &
reflection beam modes of operation are possible.
Electron
Spectroscopy
Electron spectroscopy is
an analytical technique to study the electronic structure and its dynamics
in atoms and molecules. In
general, an excitation source such as X-rays, electrons or synchrotron radiation will eject an electron from an inner-shell orbital of
an atom. Detecting photoelectrons that
are ejected by X-rays is called X-ray Photoelectron
Spectroscopy (XPS) or electron spectroscopy for chemical analysis (ESCA).
Detecting electrons that are ejected from higher orbitals to conserve energy
during electron transitions is called Auger electron spectroscopy (AES).
Electron
Spin Resonance (ESR)
The paramagnetic
substances which contain unpaired electrons when subjected to a magnetic field,
the energy levels corresponding to an electron will split up. When we apply an
oscillating field in perpendicular direction whose frequency lies in microwave
region then resonance occurs and electrons in lower energy state will absorb
energy giving rise to absorption spectra. The spectrum is known as ESR.
Electron
State
It is one of a
set of discrete, quantized energies that are allowed for electrons. In the
atomic case, each state is specified by four quantum numbers.
Electron
Volt
The energy gained
by electron when put under potential difference of 1 volt. It is equal to 1.6 x
10-19 J.
Electronics
Branch of applied
physics, which deals with devices made of semi-conductor materials having
electrons/holes as charge carriers. The branch includes study and application
of active/passive devices for various scientific and technology applications.
Electroplating
See electro deposition.
Electropositive
Chemical property
which describes tendency of an atom to lose valance electrons.
Electroscope
It was the first
electrical measuring instrument used to detect presence and magnitude of
electric charge on a body.
Electrostatic
Lens
Device used to focus electron beam.
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