Base damage by direct effects

The use of 193 nm light has been reviewed [69] but more recently it has been confirmed that guanine is the major site for localisation of the oxidative damage [72,77], consistent with the findings from esr studies. 193 nm light ionises DNA in aqueous solution with a quantum yield of -0.05 as shown in equation 5. 

The solutions generally contain oxygen to scavenge the hydrated electron, which is readily observed optically at early times [72,78]. Although all the bases will 

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