Stabilities of nanohydrated thymine radical cations: insights from multiphoton ionization experiments and ab initio calculations

摘要

Multi-photon ionization experiments have been carried out on thymine-water clusters in the gas phase. Metastable HO loss from T(HO) was observed at ≥ 3 only. Ab initio quantum-chemical calculations of a large range of optimized T(HO) conformers have been performed up to = 4, enabling binding energies of water to be derived. These decrease smoothly with , consistent with the general trend of increasing metastable HO loss in the experimental data. The lowest-energy conformers of T(HO) and T(HO) feature intermolecular bonding via charge-dipole interactions, in contrast with the purely hydrogen-bonded neutrals. We found no evidence for a closed hydration shell at = 4, also contrasting with studies of neutral clusters.