forbidden line

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Related to Forbidden mechanism: Forbidden transition, Forbidden lines

forbidden line

[fər¦bid·ən ′līn]
(atomic physics)
A spectral line associated with a transition forbidden by selection rules; optically this might be a magnetic dipole or electric quadrupole transition.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.