Tunneling in Electron Transfer Reactions of Excited Molecules

3 Tunneling in Electron Transfer Reactions of Excited Molecules 

It is well known that excitation of molecules to higher electronic states leads to a decrease in their ionization potential [35]. Therefore it could be expected that excitation of donors will increase the probability of electron tunneling from these donors to acceptors so that at sufficiently high acceptor concentrations (that is at short enough distances between donor and acceptor particles) the sub-barrier electron transfer (tunneling) from a donor to acceptor will compete with the over-barrier transfer. 

Since that time there have been a lot of publications on photoinduced electron tunneling reactions in various fields of chemistry and biology. In the present review an attempt is made to consider comprehensively both theoretical and experimental data which have been obtained to date on photoinduced electron tunneling reactions and to discuss the role played by these reactions in different areas of chemistry and biology. 

2 Inter molecular Electron Tunneling in PET Reactions with Non-Biological Molecules 

As already noted above, the first experimental evidence of electron tunneling from excited donor particles to acceptors was obtained independently in Refs. [37] and [38]. 

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