Destruction of deoxyribose induced by core-ionization

Fujii, Kentaro; Izumi, Yudai; Narita, Ayumi; Yokoya, Akinari; Herv du Penhoat, M.-A.*; Ghose, K.*; Vuilleumier, R.*; Gaigeot, M.-P.*; Politis, M.-F.*

In order to reveal a role of hydration water on the destruction of dR molecule induced by core electron ionization, we measured a mass spectrum of desorbed ions from the hydrated dR film exposed to soft X-rays with energy above oxygen K-shell ionization threshold (560 eV). The spectral changes of X-ray absorption near edge structure (XANES) of the films after the soft X-ray exposures were also examined the chemical structure of the irradiation products. The yield of the desorbed ions, which were produced by the destruction of furanose ring structure, obviously decreased with depositing one layer of water molecules on the film. This result suggests that the hydration water layer on dR film suppresses an intense destruction of the furanose ring structure of dR induced by the core ionization, or the desorption of the resulting fragment ions from the sample film. We also observed new peaks emerging around 534-536 eV in the XANES spectrum of the hydrated sample irradiated. These new peaks are located at the similar energies to those of XANES peaks of formic acid. The hydration water could also contribute to produce the newly forming products containing a carboxyl group.