Boundary-activated dissociation in a low pressure linear quadrupole ion trap in the presence of nonlinear DC fields.

Boundary-Activated Dissociation (BAD) of multiple charge ions has been investigated in a low pressure linear ion trap (LIT) in the presence of nonlinear DC fields. Nonlinear DC fields allowed ions to be stored for a long duration at working points beyond the βy = 0 stability boundary of the regular quadrupole fields. The ions reached large stable radial amplitude trajectories gaining high kinetic energies from the drive RF field. This led to collision activation and the formation of fragments. Experimental and simulation data showed that the degree of fragmentation was strongly dependent on the q value, Mathieu stability parameter, and the strengths of nonlinear fields. In the absence of the nonlinear fields the fragmentation efficiency was 0% at q = 0.23 and 17% at q = 0.4. In the presence of nonlinear fields BAD efficiency increased to up to 94% at q = 0.23 and 84% at q = 0.4. The broadening of the stability diagram at the βy = 0 boundary also enabled the observation of fragment ions with higher mass-to-charge ratios (m/z) than the m/z of the precursor ions thus overcoming a major drawback of BAD of multiple-charged ions.