https://doi.org/10.1351/goldbook.J03360
Originally, a diagram showing that the fluorescent state of a
molecular entity
is the lowest
excited state
from which the transition to the
ground state
is allowed, whereas the phosphorescent state is a
metastable
state below the fluorescent state, which is reached by
radiationless transition
. In the most typical cases the fluorescent state is the lowest singlet
excited state
and the phosphorescent state the lowest
triplet state
, the
ground state
being a singlet. Presently, modified Jablonski diagrams are frequently used and are actually state diagrams in which molecular electronic states, represented by horizontal lines displaced vertically to indicate relative energies, are grouped according to multiplicity into horizontally displaced columns.
Excitation
and
relaxation
processes that interconvert states are indicated in the diagram by arrows. Radiative transitions are generally indicated with straight arrows (→), while radiationless transitions are generally indicated with wavy arrows ⇝.
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2250 [Terms] [Paper]