Can uv light cause heterolytic cleavage?

All sources I've read stated that UV-light can only cause homolytic cleavage (homolytic fission), producing radicals while not mentioning whether it was possible for it to cause heterolytic cleavage instead. Hence is it possible for UV-light to result in heterolytic bond cleavage?




It is just a matter of energy of a single photon. Heterolytic cleavage of a symmetric bond requires more energy and can be less brobable, but see the [totalitarian principle](https://en.wikipedia.org/wiki/Totalitarian_principle).


E.g. the extreme UV (tens of eV per photon) can indiscriminately cleave any chemical bond both homolytically and heterolytically.


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