Photoinduced electron transfer

[1][2] Due to PET a charge separation is generated, i.e., redox reaction takes place in excited state (this phenomenon is not observed in Dexter electron transfer).

Such materials include semiconductors that can be photoactivated like many solar cells, biological systems such as those used in photosynthesis, and small molecules with suitable absorptions and redox states.

The end result of both reactions is that an electron is delivered to an orbital that is higher in energy than where it previously resided.

In the absence of a proper electron donor or acceptor it is possible for such molecules to undergo ordinary fluorescence emission.

If the electron is not kinetically isolated thermodynamics will take over and the products will react with each other to regenerate the ground state starting material.