Higher-energy UV radiation

In the excited singlet state the ionization potential of the molecule is reduced, and the excited electron is more easily removed compared to the ground state. This process of photoionization is also more likely to occur if higher energy UV radiation is used (i.e., wavelengths less than 300 nm) and if the drug molecule is in its anionic state. An example is naproxen in aqueous solution at pH 7, where the process of decarboxylation occurs and a neutral radical is formed (11), Reaction 7 ... 

Because the chemical bonds in oxygen are stronger than the chemical bonds in ozone, oxygen absorbs higher-energy UV radiation than does ozone. 

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