| SAM | S-adenosyl-L-methionine; scanning acoustic microscope; senescence accelerated mouse; sex arousal mec... |
|---|---|
| SLAM | scanning laser acoustic microscope; systemic lupus erythematosus activity measure |
| SLIC | scanning liquid ionization chamber |
| SR | sarcoplasmic reticulum; saturation recovery; scanning radiometer; screen; secretion rate; sedimentat... |
| STM | scanning tunneling microscope; short-term memory; streptomycin |
| 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) |
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| reverse electron transport | <chemistry> The energy-dependent movement of electrons against the thermodynamic gradient to form a strong reductant from a weaker electron donor. (11 Jan 1998) |
| microscope, electron | <microscopy> An electron-optical device which produces a magnified image of an object. Detail may be revealed by virtue of selective transmission, reflection, or emission of electrons by the object. (05 Aug 1998) |
| Convergent Beam Electron Diffraction | <microscopy> An electron probe is tightly focused on a transmission electron microscopy specimen and the resulting pattern of diffracted electrons is observed. The patterns contains information on the crystal symmetry and atomic and electronic structure of the sample. Regions as small as 0.2 nm may be examined. Acronym: CBED (05 Aug 1998) |
| conversion electron | An internal conversion electron. (05 Mar 2000) |
| positive electron | A subatomic particle of mass and charge equal to the electron but of opposite (i.e., positive) charge. Synonym: positive electron. (05 Mar 2000) |
| secondary electron | <microscopy> Produced by an incident electron passing near an atom in the specimen, near enough to impart some of its energy to a lower energy electron (usually in the K-shell). This causes a slight energy loss and path change in the incident electron and the ionisation of the electron in the specimen atom. This ionised electron then leaves the atom with a very small kinetic energy (5eV) and is then termed a secondary electron. Each incident electron can produce several secondary electrons. (05 Aug 1998) |
| secondary electron imaging | <microscopy> Production of secondary electrons is very topography related. Due to their low energy, 5eV, only secondaries that are very near the surface (less than 10nm) can exit the sample and be examined. Any changes in topography in the sample that are larger than this sampling depth will change the yield of secondaries due to collection efficiencies. Collection of these electrons is aided by using a collector in conjunction with the secondary electron detector. The collector is a grid or mesh with a +100V potential applied to it which is placed in front of the detector, attracting the negatively charged secondary electrons to it which then pass through the grid-holes and into the detector to be counted. When a Secondary Electrons collide with the solid-state saemiconductor detector an electron-hole pairs are created which are then counted. This quantity is translated into a pixel intensity and displayed on the CRT, forming the image. (05 Aug 1998) |
| Selected Area Electron Diffraction | <technique> In this diffraction mode an aperture is used to define the area from which a diffraction pattern is to be recorded from a thin sample. This aperture is typically located in an image plane below the sample. Selected Area Electron Diffraction patterns are simple spot patterns and are of use in phase determination (lattice spacing measurement) and defect analysis (sample orientation). Acronym: SAED (05 Aug 1998) |
| internal conversion electron | An electron, similar to an Auger electron, released from one of the electron orbits of the atom upon activation by a gamma-ray from that atom's nucleus; the electron has kinetic energy equal to the net energy transition of the disintegration. (05 Mar 2000) |
| electron | <chemistry, physics> A stable atomic particle that has a negative charge, the flow ofelectrons through a substance constitutes electricity. (19 Jan 1998) |
| electron acceptor | <chemistry> A molecule or compound that gets electrons during an oxidation-reduction reaction. (19 Jan 1998) |
| electron beam | <microscopy> A stream of electrons in an electron optical system. (05 Aug 1998) |
| electron capture | <radiobiology> Nuclear decay process whereby a proton in the nucleus absorbs an orbiting electron and converts to a neutron. (09 Oct 1997) |
| electron carrier | <chemistry> A protein which can either accept or donate electrons in oxidation-reduction reactions. (19 Jan 1998) |