A detailed study on the decomposition pathways of the amino acid valine upon dissociative electron attachment

In the present study we investigate free electron attachment to the amino acid valine. Mass spectra and anion efficiency curves are measured in the electron energy range from about zero eV to about 15 eV and the anionic fragments are analyzed with a double focusing mass spectrometer. The high sensitivity of the present setup allows the detection of 10 fragment anions that have not been reported before and the high mass resolution of our sector field mass spectrometer allows us the separation and identification of isobaric anions. Thus the isobaric ion pairs, CN^-/C₂H₂^-_2^-, and O^-/NH₂^-_2^-, can be identified and assigned to individual resonances. For some of the heavier fragment anions formed we have studied collision induced dissociation to collect more information on the structures of these anions.