The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
a quantity used in spectroscopy, which is proportional to the steady-state energy of an atom or molecule. Spectral terms were first introduced empirically in the analysis of regularities of the positions of lines in spectra.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.