Photodissociation dynamics of adenine dimer radical ions and hydrated adenine dimer ions, (n = 0–6)

We studied photodissociation dynamics of adenine dimer radical ions, A 2 + , and hydrated adenine dimer ions, A 2 + ( H 2 O ) n (n = 1–6), at three wavelengths. The most abundant daughter ion is found to be protonated adenines, (AH)+, which implies that proton transfer is followed by dissociation in A 2 + and A 2 + ( H 2 O ) n . Theoretical calculations support that the most stable structures of A 2 + and A 2 + ( H 2 O ) 1 are formed by proton transfer. As cluster size of A 2 + ( H 2 O ) n becomes larger, the intensity of A 2 + as a daughter ion increases with the decrease in the intensity of (AH)+. Upon photoexcitation of A 2 + by 266 nm, adenine monomer ion (A+) is also observed along with (AH)+, which suggests that electronically excited states of (AH)+ moiety in A 2 + promotes the hydrogen abstraction from (AH)+.