Hydrogen release from charged fragments of the uracil cation followed by their fragmentation: A DFT study

The possible fragmentation mechanisms of the uracil cation have been investigated through DFT calculations. The comparison between the peak intensity obtained from a mass spectrum for given mass/charge ratios and the required energy to form given fragments, allows one to propose a fragmentation channel. Particular attention has been brought to the possible hydrogen release from formed and activated fragments that might occur during the fragmentation process. Although the H-loss has never been observed experimentally through direct mechanism impact of high energy particles, it is predicted from calculated free energy to be a highly possible process.