0In molecular spectroscopy, a Jablonski diagram is a diagram which illustrates the electronic states of a molecule and also the transitions between them. The states are arranged vertically by energy and grouped horizontally by spin multiplicity.
Nonradiative transitions are indicated by squiggly arrows and radiative transitions by straight arrows.
Question type1: The average lifetime of phosphorescence is higher than fluorescence. Explain
with Jablonski diagram. (Previous year question 2016)
- Phosphorescence is a type of photoluminescence related to fluorescence. Unlike fluorescence,phosphorescent material does not immediately re-emit the radiation it absorbs. The slower time scales of the re-emission are associated with "forbidden" energy state transitions in quantum mechanics.
- Fluorescence differs from phosphorescence in that the electronic energy transition that is responsible for fluorescence does not change in electron spin, which results in short-live electrons (<10-5 s) in the excited state of fluorescence.
- In phosphorescence, there is a change in electron spin, which results in a longer lifetime of the excited state (second to minutes).
