, wavenumber or frequency at which the total intensity of emission of light by a sample does not change during a chemical reaction or physical change. The terms isolampsic
are sometimes used.
This term may be misleading because it does not specifically refer to light emission.
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook