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. Author manuscript; available in PMC: 2015 Sep 8.
Published in final edited form as: Nanotechnol Rev. 2012 Mar;1(2):111–146. doi: 10.1515/ntrev-2011-0005

Figure 1.

Figure 1

Jablonski diagram.

Initial absorption of a photon by the ground state of the singlet PS gives rise to the short-lived excited singlet state. This can lose energy by fluorescence, internal conversion to heat, or by intersystem crossing to the long-lived triplet state. PS triplet states are efficiently quenched by energy transfer to molecular oxygen (a triplet state) to give type 2 (singlet oxygen) or by electron transfer to oxygen or to biomolecules to give type 1 ROS (superoxide and hydroxyl radical).