Selective Bond Cleavage in Potassium Collisions with Pyrimidine Bases of DNA

D. A. and F. F. S. acknowledge the Portuguese Foundation for Science and Technology (FCT-MEC) for a post-graduate Grant No. SFRH/BD/61645/2009 and post-doctoral Grant No. SFRH/BPD/68979/2010, respectively. We also acknowledge partial funding from the Portuguese research Grant No. PEst-OE/FIS/UI0068/2011 through FCT-MEC, and from the Spanish Ministerio de Economia y Competitividad (Project No. FIS 2009-10245). Some of this work forms part of the EU/ESF COST Actions Nano-IBCT-MP1002 and The Chemical Cosmos-CM0805. The authors are extremely grateful to Professor Eugen Illenberger from the Free University Berlin, Germany, for fruitful and lively discussions.Electron transfer in alkali-molecule collisions to gas phase thymine and uracil yielding H- formation is selectively controlled in the energy range between 5.3 and 66.1 eV. By tuning the collision energy, electron transfer from the alkali to partly deuterated thymine, methylated thymine at the N-1 and methylated uracil at the N-3 positions, H- loss proceeds not only through the breaking of the (C-H) against (N-H) bonds but also through N-1 against N-3 sites. Such selectivity, as far as bond and site are concerned, is here reported for the first time by electron transfer induced dissociation experiments in alkali-molecule collisions.publishersversionpublishe