Decompositions Occurring Remote from the Charge Site: A New Class of Fragmentation of FAB-Desorbed Ions

Abstract

For the past several years we have been involved in a research program to develop the combined techniques of fast atom bombardment and tandem mass spectrometry for structure determination [1–18]. This research has been performed on a Kratos MS-50 triple sector mass spectrometer which consists of a high resolution MS-50 as MS-I coupled to an electrostatic analyzer serving as MS-II [19]. The ion selected with MS-I has a translational energy of 8KeV and the collision process transfers up to one hundred electron volts into internal energy. This makes accessible reaction channels which are not readily found for ions with the usual range of internal energies. As a result of the high energy, a hitherto unrecognized class of reactions has been discovered. These reactions are most readily observed for closed-shell ions and occur remote from the charged site, in contrast to the common charge-induced reactions. In this paper, the experimental evidence for the nature of the reaction and the extent of its occurrence will be discussed.