Its relative rarity on Earth, like that of helium, is due to its relative lightness and chemical inertness, both properties keeping it from being trapped in the condensing gas and dust clouds of the formation of smaller and warmer solid planets like Earth. Neon is actually abundant on a universal scale: the fifth most abundant chemical element in the universe by mass, after hydrogen, helium, oxygen, and carbon (see chemical element). The average color of this light to the human eye is red-orange it contains a strong green line which is hidden, unless the visual components are dispersed by a spectroscope. Neon plasma has the most intense light discharge at normal voltages and currents of all the rare gases. In most applications it is a less expensive refrigerant than helium. Neon is the second-lightest noble gas, glows reddish- orange in a vacuum discharge tube and has over 40 times the refrigerating capacity of liquid helium and three times that of liquid hydrogen (on a per unit volume basis). Elevated 20Ne abundances are found in diamonds, further suggesting a solar neon reservoir in the Earth. The 20Ne-enriched components are attributed to exotic primordial rare gas components in the Earth, possibly representing solar neon. The neon isotopic content of these mantle-derived samples represent a non-atmospheric source of neon. Similar to xenon, neon content observed in samples of volcanic gases are enriched in 20Ne, as well as nucleogenic 21Ne, relative to 22Ne content. This suggests that neon will be a useful tool in determining cosmic exposure ages of surficial rocks and meteorites. By analyzing all three isotopes, the cosmogenic component can be resolved from magmatic neon and nucleogenic neon. This isotope is generated by spallation reactions on magnesium, sodium, silicon, and aluminium. Isotopic analysis of exposed terrestrial rocks has demonstrated the cosmogenic production of 21Ne. The net result yields a trend towards lower 20Ne/ 22Ne and higher 21Ne/ 22Ne ratios observed in uranium-rich rocks such as granites. The alpha particles are derived from uranium-series decay chains, while the neutrons are mostly produced by secondary reactions from alpha particles. The principal nuclear reactions which generate neon isotopes are neutron emission, alpha decay reactions on 24Mg and 25Mg, which produce 21Ne and 22Ne, respectively. In contrast, 20Ne is not known to be nucleogenic and the causes of its variation in the Earth have been hotly debated. 21Ne and 22Ne are nucleogenic and their variations are well understood. If you let book author know once you have cited this book, the brief information of your publication will appear on the “Times Cited” page.Neon has three stable isotopes: 20Ne (90.48%), 21Ne (0.27%) and 22Ne (9.25%). ![]() The book author ( Yougui Liao) welcomes your comments, suggestions, and corrections, please click here for submission. A P Hitchcock, and C E Brion, Neon K-shell excitation studied by electron energy-loss spectroscopy, 1980 J. King G C, Tronc M, Read F H and Bradford R C 1977 J. The main figure was obtained with a resolution of 0.37 eV FWHM (full width at half maximum) while the insert spectrum was recorded with a resolution of 0.8 eV FWHM. The EELS profile of neon in the region of 1s excitation. ![]() Figure 2661 shows the EELS profile of neon in the region of 1s excitation.įigure 2661. The electron energy-loss spectrum of gaseous neon in the region of 1s (K-shell) excitation was investigated using small-angle (2 x 10 -2 rad)) inelastic scattering of 2.5 keV electrons. The continuously variable energy loss is similar to a tuneable photon energy. At these low energies, the spectra are dipole dominated and are analogous to photoabsorption spectra obtainable with bremsstrahlung or synchrotron radiation. ![]() This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.Įlectron energy-loss spectroscopy ( EELS) has been applied to study the excitation of the inner-shell electrons of gaseous atoms and molecules with low-energy incident electrons, e.g.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |