Electron loss and dissociation in high energy collisions between multiply charged oligonucleotide anions and noble gases

We have measured electron loss cross sections and fragment spectra for collisions between multiply charged oligonucleotide anions and noble gas atoms. The ions were produced in an electrospray source and accelerated through a potential difference of 50kV before collisions with the target gas. The collision cross sections depend on the charge state of the projectile ions and on the target gas. The fragment spectra provide information about the sequences of oligonucleotides. The major sequence ions are w and a-B ions. Radical ions as a result of electron loss lead to a ions and cleavage of the sugar ring. Double-electron loss is found to be the first step toward formation of b ions.