![]() ![]() In this variation, known as energy-dispersive X-ray fluorescence analysis (EDXRFA or XRF), the electron column is replaced by an X-ray tube and the X-rays emitted by the sample in response to the bombardment are called secondary X-rays, but these variants are otherwise identical. It is also possible to use X-rays to excite the core electrons to the point of ionization. ![]() For comprehensive numerical tables of A, f, and S, including forbidden lines (see. (22) The Aki values for strong lines of selected elements are given. The detector is cooled to liquid nitrogen temperatures to reduce electronic noise from thermal excitations. Thus for the lower (upper) level of a spectral line, gi(k) 2 Ji(k) + 1, and for the lower (upper) term of a multiplet, gi ( k) i ( k) (2Ji ( k) + 1) (2Li ( k) + 1)(2Si ( k) + 1). This promotes electrons in the plate into the conduction band, inducing a voltage proportional to the energy of the impacting X-ray which generally falls between about 1 and 10 keV. The beam is produced by an electron gun, in which electrons emitted thermionically from a hot cathode are guided down the column by an electric field and focused by a series of negatively charged “lenses.” X-rays emitted by the sample strike a lithium-drifted silicon p-i-n junction plate. The first is to use a high-energy electron beam like the one in a scanning electron microscope (SEM). There are two common methods for exciting the core electrons off the surface atoms. Adapted from Introduction to Energy Dispersive X-ray Spectroscopy (EDS), /public/manuals/EDS-intro.pdf. The arrows show the direction the vacancy moves when the higher energy electrons move down to refill the core. Department of Energy, by the National Aeronautics and Space Administration, by NIST's Standard Reference Data Program (SRDP), and by NIST's SMA Program.\) A diagram of the energy transitions after the excitation of a gold atom. This database was funded by the Office of Fusion Energy Sciences of the U.S. Online: March 1995 - Last update: October 2022 ![]() All rights reserved. NIST reserves the right to charge for these data in the future. Department of Commerce on behalf of the United States. Past Contributors: Haris Kunari, Jean E. Sansonetti, Jeffrey R. Fuhr, Larissa I. Podobedova, Wolfgang L. Wiese, John J. Curry, Gerry R. Dalton, Robert Dragoset, Fun-Chen (Jesse) Jou, William C. Martin, Peter J. Mohr, Arlene Musgrove, Craig J. Sansonetti, and Gloria Wiersma Students contributing to data entry: Eric Carpentier, Thomas Carpentier, Amy Zimmerman, Adrian Hamins-Puertolas, Marko Hamins-Puertolas, Anna Sharova, Genevieve Tan NIST ASD Team Principal Developers (Currently Active): Alexander Kramida, Yuri Ralchenko, and Joseph Readerĭata Compilers (Currently Active): Alexander Kramida, Edward B. Salomanĭatabase Developers (Currently Active): Alexander Kramida, Yuri Ralchenko, and Karen Olsen The Data Center is located in the Physical Measurement Laboratory at the National Institute of Standards and Technology (NIST). The Atomic Spectroscopy Data Center has carried out these critical compilations. This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. Help - On-line help in using the database.
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