energetics
| atomic volume | The atomic weight of an element divided by its density in the solid state; the volume of the gram-atomic weight of a solid element. (05 Mar 2000) |
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| atomic weight | <chemistry> The average weight of an atom of an element, i.e. The total mass of protons and neutrons in an atom. (09 Oct 1997) |
| gram-atomic weight | Atomic weight expressed in grams. Compare: mole. (05 Mar 2000) |
| microscopy, atomic force | Microscopy in which a probe systematically rides across the surface of a sample being scanned in a raster pattern. The vertical position is recorded as a spring attached to the probe rises and falls in response to peaks and valleys on the surface. A microcomputer keeps track of the vertical excursions as a function of the position of the probe in the horizontal plane and presents the sample's image. (12 Dec 1998) |
| spectrophotometry, atomic absorption | A highly sensitive technique used to analyze various elements, especially metals, including aluminum, arsenic, beryllium, calcium, copper, iron, lead, and lithium, which are present in trace amounts. The atoms are excited above a ground state by flame vaporization, and the radiation emitted as the molecules return to a ground state is measured in unexcited non-ionised molecules. (12 Dec 1998) |
| activation energy | <chemistry> The amount of energy (expressed in joules) that is needed to convert all the molecules in one mole of a reacting substance from a ground state to the transition state. (06 May 1997) |
| binding energy | <chemistry, radiobiology> The binding energy of a nucleus is the minimum energy required to dissociate it into its component neutrons and protons. Neutron or proton binding energies are those required to remove a neutron or proton, respectively, from a nucleus. Electron binding energy is that required to remove an electron from an atom or a molecule. (16 Dec 1997) |
| bioelectric energy sources | Implantable devices which convert biological energy (chemical energy of the metabolism of continuously regenerating body fluids or mechanical energy of periodic movements) to electrical energy. The sources include biogalvanic cells, biofuel cells, and ionic concentration cells. (12 Dec 1998) |
| biomass energy | See Bioenergy. (05 Dec 1998) |
| bond dissociation energy | This is the energy needed to break the bonds between two linked atoms. (09 Oct 1997) |
| bond energy | The energy needed to break a molecular bond. (09 Oct 1997) |
| radiant energy | Energy contained in light rays or any other form of radiation. (05 Mar 2000) |
| radiography, dual-energy scanned projection | A method of producing a high-quality scan by digitizing and subtracting the images produced by high- and low-energy X-rays. (12 Dec 1998) |
| radiotherapy, high-energy | Radiotherapy using high-energy (megavolt or higher) ionizing radiation. Types of radiation include gamma rays, produced by a radioisotope within a teletherapy unit; X-rays, electrons, protons, alpha particles (helium ions) and heavy charged ions, produced by particle acceleration; and neutrons and pi-mesons (pions), produced as secondary particles following bombardment of a target with a primary particle. (12 Dec 1998) |
| Parallel Electron Energy Loss Spectroscopy | <technique> Electron energy loss spectroscopy analyses the inelastically scattered electrons present in the beam after it has been transmitted through the sample. An electron energy loss spectrum typically consists of a monatomic decreasing background on which are superimposed a number of peaks. Each peak is characteristic of the scattering process that has occurred in the sample. The peaks can be used to obtain information about the chemical composition and electronic structure of the sample. Electron energy loss spectra are acquired typically in a magnetic sector spectrometer located under the camera chamber of the transmission electron microscope. Spatial resolution is typically limited by the minimum probe diameter of the microscope. Electron energy loss spectroscopy tends to be complimentary to EDS in that it can be used to analyse very thin samples of low Z materials. Acronym: PEELS (05 Aug 1998) |