© 2002 J.Paul Robinson, Purdue University
Phosphorescence
•Following absorption, molecules can relax via a non-radiative transition
to the T1 rather than the S1 state - this is called an intersystem crossing,
•While it is forbidden it does happen and has a low
probability and takes a
longer time - the energy dissipated is called phosphorescence
•Phosphorescence has a longer lifetime than
fluorescence (milliseconds
rather than femptoseconds
•Phosphorescence generally occurs at longer wavelengths
than fluorescence because
the energy difference between S0 and T1 is lower
Shapiro p 88
