Photodissociation dynamics of adenine dimer radical ions and hydrated adenine dimer ions , A þ 2 ð H 2 O Þ n ( n = 0 – 6 )

We studied photodissociation dynamics of adenine dimer radical ions, A2 , and hydrated adenine dimer ions, A þ 2 ðH2OÞn (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 A2 and A þ 2 ðH2OÞn. Theoretical calculations support that the most stable structures of A þ 2 and A þ 2 ðH2OÞ1 are formed by proton transfer. As cluster size of A2 ðH2OÞn becomes larger, the intensity of A þ 2 as a daughter ion increases with the decrease in the intensity of (AH). Upon photoexcitation of A2 by 266 nm, adenine monomer ion (A ) is also observed along with (AH), which suggests that electronically excited states of (AH) moiety in A2 promotes the hydrogen abstraction from (AH) . 2007 Elsevier B.V. All rights reserved.