This work aims to study oligonucleotides and mononucleotides by new fragmentation techniques such as EDD (electron-detachment-dissociation) and EID (electron-induced-dissociation) involving electron bombardment. The samples are first ionized by an electrospray source (ESI), which allows a soft ionization. During my PhD, I have been interested in the study of smaller oligonucleotides (DNA and RNA single strands) and mononucleotides by EDD and EID. First the different parameters have been optimized in order to obtain by ESI multicharged species to study the EDD process of oligonucleotides with different charge states. These spectra are compared with SORI-CID spectra (Collision-Induced-Dissociation) and IRMPD (Infrared Multiphoton-Dissociation-) to highlight the specificities of the EDD and EID. Compared to SORI-CID, EDD and EID spectra show some fragment ions, which are not observed in the SORI-CID and IRMPD spectra because they do not lead to radical ions. Thanks to the radical fragment ions obtained by EDD and EID, we were able to access the sequencing oligonucleotides rich in thymine for which it is difficult to obtain information by conventional methods. Finally we used special techniques of ICR technology which will be presented in this manuscript
