occurring by tunnelling
from a 'bound
' to an 'unbound
' vibronic state. In an absorption spectrum
of a molecular entity, the appearance of a diffuse band region within a series of
sharp bands is called predissociation, since irradiation
with frequencies within the diffuse region leads to effective dissociation
. The energy of the band is smaller than that of the dissociation
continuum of the bound state.
PAC, 1996, 68, 2223
(Glossary of terms used in photochemistry (IUPAC Recommendations 1996))
on page 2266
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. https://doi.org/10.1351/goldbook