Field ion microscopy techniques were initially construed as a modification of field emission, a technique which allows for a stream of electrons to be emitted from a sharp needle when subjected to a sufficiently high electric field (~ 3-6 V / nm ).

For field ion microscopy a gas is introduced, known as the imaging gas, into the chamber at very low pressures.

Therefore the ion speed can be computed with the following equation, which relates kinetic energy to energy gain due to the electric field.

This magnification is sufficient to observe field variations due to individual atoms, thus allowing in field ion and field evaporation modes for the imaging of single atoms.

Whilst the magnification of both the field ion and atom probe microscopes is extremely high, the exact magnification is dependant upon conditions specific to the examined specimen, so unlike for conventional electron microscopes, there is often little direct control on magnification, and furthermore, obtained images may have strongly variable magnifications due to fluctuations in the shape of the electric field at the surface.

A key feature of the evaporation or field ion images is that the data density is highly inhomogeneous, due to the corrugation of the specimen surface at the atomic scale.

Initial field ion microscopes, precursors to modern atom probes, were usually glass blown devices developed by individual research laboratories.

Dislocations can be observed using transmission electron microscopy, field ion microscopy and atom probe techniques.

* Fourier transform ion cyclotron resonance mass spectrometry to determine the mass of ions from the frequency of cyclotron motion in a magnetic field.

The field ion microscope is a type of microscope that can be used to image the arrangement of atoms at the surface of a sharp metal tip.

*** Ion-sensitive field effect transistor, to measure ion concentrations in solution.

* Chemistry: Molecular theory — Kinetic theory of gases — Molecular orbital theory — Valence bond theory — Transition state theory — RRKM theory — Chemical graph theory — Flory-Huggins solution theory — Marcus theory — Lewis theory ( successor to Brønsted – Lowry acid – base theory ) — HSAB theory — Debye – Hückel theory — Thermodynamic theory of polymer elasticity — Reptation theory — Polymer field theory — Møller – Plesset perturbation theory — Density Functional Theory — Frontier molecular orbital theory — Polyhedral skeletal electron pair theory — Baeyer strain theory — Quantum theory of atoms in molecules — Collision theory — Ligand field theory ( successor to Crystal field theory ) — Variational Transition State Theory — Benson group increment theory — Specific ion interaction theory

In spacecraft propulsion, a Hall thruster is a type of ion thruster in which the propellant is accelerated by an electric field.

Electrostatic ion thrusters use the Coulomb force and accelerate the ions in the direction of the electric field.

* Electrostatic ion thrusters use the Coulomb force and are categorized as accelerating the ions in the direction of the electric field.

These electrons can be provided from a hot cathode filament and when accelerated in the electrical field of the cathode, fall to the anode ( Kaufman type ion thruster ).

Then this atom of calcium will swell to something like a great balloon a hundred yards across, a balloon big enough to put a football field inside.

Even if the atom were big enough to hold a football field, this nucleus is still only about the size of a pinhead.

Nevertheless, the basic idea of the atom was adopted by scientists thousands of years later because it elegantly explained new discoveries in the field of chemistry.

These ions, under the influence of the electric field, are accelerated into the cathode surface containing the sample, bombarding the sample and causing neutral sample atom ejection through the process known as sputtering.

Furthermore, in normal operation ( as opposed to a field ionization modes ) the atom probe does not utilize a secondary source to probe the sample.

Field evaporation is an effect that can occur when an atom bonded at the surface of a material is in the presence of a sufficiently high and appropriately directed electric field, where the electric field is the differential of electric potential ( voltage ) with respect to distance.

Once this condition is met, it is sufficient that local bonding at the specimen surface is capable of being overcome by the field, allowing for evaporation of an atom from the surface to which it is otherwise bonded.

Semi-conductor materials are often analysable in atom probe, however sample preparation may be more difficult, and interpretation of results may be more complex, particularly if the semi-conductor contains phases which evaporate at differing electric field strengths.

Electrons are the charge carriers in metals and they follow an erratic path, bouncing from atom to atom, but generally drifting in the opposite direction of the electric field.

The number of ligands that react with a central metal atom can be found using the 18-electron rule, saying that the valence shells of a transition metal will collectively accommodate 18 electrons, whereas the symmetry of the resulting complex can be predicted with the crystal field theory and ligand field theory.

The effect of the field in this case is to reduce the effective binding energy of the atom to the surface and to give, in effect, a greatly increased evaporation rate relative to that expected at that temperature at zero fields.

The hydrogen atom has special significance in quantum mechanics and quantum field theory as a simple two-body problem physical system which has yielded many simple analytical solutions in closed-form.

An external electromagnetic field at a frequency associated with a transition can affect the quantum mechanical state of the atom.

As the electron in the atom makes a transition between two stationary states ( neither of which shows a dipole field ), it enters a transition state which does have a dipole field, and which acts like a small electric dipole, and this dipole oscillates at a characteristic frequency.

Magnetic flux from the surroundings ( such as other wires ) may diminish or enhance the field the Hall probe intends to detect, rendering the results inaccurate.

All such methods imply a solid probe tip in the ( near field ) of an object, which is supposed to be almost flat.

Alternatively, microscopes can be classed on whether they analyse the sample via a scanning point ( confocal optical microscopes, scanning electron microscopes and scanning probe microscopes ) or analyse the sample all at once ( wide field optical microscope and transmission electron microscopes ).

It carried a complement of experiments to probe Venus ' atmosphere with radio waves, scan its brightness in ultraviolet light, and sample the solar particles and magnetic field fluctuations above the planet.

Mariner 5 ( Mariner Venus 1967 ) was a spacecraft of the Mariner program that carried a complement of experiments to probe Venus ' atmosphere by radio occultation, measure the hydrogen Lyman-alpha ( hard ultraviolet ) spectrum, and sample the solar particles and magnetic field fluctuations above the planet.

NMR measurements probe the local magnetic field around an atom and hence reflect the susceptibility of the material.

* 1967-Erwin Wilhelm Müller adds time-of-flight spectroscopy to the field ion microscope, making the first atom probe and allowing the chemical identification of each individual atom.

A reciprocating probe is mounted on an arm that is moved into and back out of the plasma, usually in about one second by means of either a pneumatic drive or an electromagnetic drive using the ambient magnetic field.

The Mars Observer spacecraft, also known as the Mars Geoscience / Climatology Orbiter, was a 1, 018-kilogram ( 2, 244 lb ) robotic space probe launched by NASA on September 25, 1992 to study the Martian surface, atmosphere, climate and magnetic field.

Preliminary mission goals expected the probe to provide planetary magnetic field data, detection of certain spectral line signatures of minerals on the surface, images of the surface at 1 meter / pixel and global elevation data.

The Magsat satellite and later satellites have used 3-axis vector magnetometers to probe the 3-D structure of the Earth's magnetic field.

As it passed Jupiter, the probe ' fell ' through the planet's gravity field, exchanging momentum with the planet ; this gravity assist maneuver bent the probe's trajectory up out of the planetary plane into an orbit that passed over the poles of the Sun.

In the field of engineering, engineers probe or study the inputs and outputs of components to understand their functionality.

Recent images from the Cassini probe show that the Promethean gravitational field creates kinks and knots in the F Ring as the moon ' steals ' material from it.

When the Hall Probe is held so that the magnetic field lines are passing at right angles through the sensor of the probe, the meter gives a reading of the value of magnetic flux density ( B ).

The probe handle, being made of a non-ferrous material, has no disturbing effect on the field.