K-edge


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K-edge

In radiography, the sharp increase in characteristic x-ray production resulting when the incoming x-ray beam matches the K-shell-binding energy of an atom. K-edge production can cause problems in predicting radiation exposure; i.e., when kilovolts peak is decreased and the K-edge is matched by the incoming x-ray photons, image density may increase.
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Contract notice: Support and maintenance of the open vms-based hybrid k-edge / xrf software
Iodine attenuation increases at lower tube potentials due to decreased Compton scattering and greater photoelectric effect when photon energy approaches the k-edge of iodine (33.2 keV).
Preclinical results with spectral molecular CT have been very encouraging and indicate that the specific identification and quantification of tissue types and nanoparticles is possible, such as imaging of vulnerable plaque [11,12], soft tissue quantification [13], reduction in metal-related CT artefacts [14,15], crystal-induced arthropathies [16,17], quantitative imaging of excised osteoarthritic cartilage [18], and K-edge imaging of high-Z (atomic number) biomedical nanoparticles [19,20].
Previous report suggested that lower energy level (approaching the K-edge of iodine) increases the attenuation of iodine because of the predominance of the photoelectric effect [10].
The excitation energy for fluorescence mapping was 3.0 keV for Al K-edge mapping and 7.2 keV for Fe K-edge mapping.
deals with sulfur (S) speciation in the surface sediments of lakes from different regions of China, using S K-Edge XANES spectroscopy, which has unique advantages in morphological analysis of S in sediments.
Figure 2(b) displays the C K-edge XANES spectra of FLG and MWCNTs and the reference graphite.
The carbon and nitrogen K-edge X-ray absorption near-edge structure (XANES) measurement of the samples were performed at the beamline 4B7B of Beijing Synchrotron Radiation Facility (BSRF).
In order to identify the mineralogical transformation during the process and how they affect the sulfurremoval efficiency, the morphology of mineral surface, mineral composition, and sulfur speciation on mineral surface was analyzed by combined techniques such as SEM, XRD, and sulfur K-edge X-ray absorption near edge spectroscopy (XANES), respectively.
An experimental evaluation of the atomic photo effect cross section at K-edge can be carried out by an one of the following methods (i) measurement of K-X ray yield, following the ejection of photo electron, (ii) measurement of the photo electron intensities and (iii) extra polation method.
Element Data (1) Off the K-absorption edges, the mass-absorption coefficient that rules the X-ray absorption is proportional to [Z.sup.3] Element Z Density K-Edge [g/c[m.sup.3]] [keV] Bismuth 83 9.8 90.5 Lead 82 11.3 88.0 Gold 79 19.3 80.7 Tin 50 7.3 29.2 Silver 47 10.5 25.5 Copper 29 9.0 9.0 Carbon 6 2.2 0.3 References
The compound, BaF ([Br.sub.85%][I.sub.15%]), is used as the phosphor and has a primary radiation absorption K-edge of' barium at 37.4 keV and a much smaller absorption K-edge of iodine at 13.4 keV.