parahelium
parahelium
[‚par·ə′hē·lē·əm] (atomic physics)
Those states of helium in which the spins of the two electrons are antiparallel, in contrast to orthohelium. Also spelled parhelium.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive
Expulsion of an activated helium atom ([He.sup.*]) can lead to two conditions, depending on whether the electrons within this species are antiparallel (
parahelium) or parallel (orthohelium).
Likewise, if the ground state electron is 'spin up', the excited electron must be 'spin down' to enable the transition, He* [right arrow] He + h v, again producing the identical He I lines from singlet state
parahelium.
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