Collision-Induced Dissociation of Hydrated Adenosine Monophosphate Nucleotide Ions: Protection of the Ion in Water Nanoclusters

Fragmentation of singly charged anions of adenosine 5'-monophosphate (AMP^-) induced by collisions with neutral atoms (Ne, Na) has been studied at a collision energy of 50 keV. The experiments were performed with isolated AMP^- as well as with AMP^- anions nanosolvated in a cluster with a given number m of water molecules. In the first case, the dominant fragmentation channels concern the loss of adenine, PO₃^- and H₂PO₄^-. In the latter, loss of water molecules becomes the dominating process, and the AMP^- ion is fully protected when m is larger than ~13. The observed fragment distributions are well described with the model of an evaporative ensemble.