from the primary excited atomic or molecular species at the wavelength
of the exciting radiation (no relaxation
within the excited manifold). This term is also used to designate the radiation emitted
by an atom of the same wavelength
as the longest one capable of exciting its fluorescence
in the case of the hydrogen atom, and
in the case of the mercury atom.
PAC, 1996, 68, 2223
(Glossary of terms used in photochemistry (IUPAC Recommendations 1996))
on page 2271
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