Modeling dipolar excitation for quadrupole mass filter

Abstract

The results of modeling AC and DC dipole excitation of ion oscillations in a quadrupole mass filter are presented. The simulation is done by numerical integration of the ion motion equations, ions’ initial coordinates and velocities are distributed normally. For AC dipole excitation the instability bands on the ( a, q) stability diagram follow along the isolines [Formula: see text] and [Formula: see text], creating regular dips on the transmission contour. We show that AC excitation at frequency Ω/2 makes it possible to control the resolution of the mass filter by either changing the AC amplitude or phase. Instability bands can be used for mass selective excitation in a linear ion trap. Options for the joint use of DC and AC dipole excitation to form the mass peak shape are considered.

Dipole and quadrupole resonance excitation in linear quadrupoles

“…The possibility of using additional DE for mass analysis of the linear quadrupole is considered in. [51][52][53][54][55][56][57] The QMF with DE is described in the patent [(a)]. The idea of the method is to change the stability boundaries of the first region by removing the stable boundary by DE.…”

“…For zero frequency ν y = 0, the equation of motion along the y coordinate is written in the following form 55 :…”

“…Transmission contour (mass peak) with dipole excitation at frequency ν x = 0.47 and amplitude q x = 0.0005. The scan parameter λ = 0.165 55.…”

“…Transmission contours at two values of the parameter λ: 0.166 (a) and 0.1667 (b). Dipole excitation at the frequency ν x = 0.5 55.…”

“…(a)The potential DC = 0.0002 is constant and the resolution is changed by increasing the amplitude q x . (b) Simultaneous change of DC and AC q x potentials 55.…”