Experimental Observation of the Effects of Translational and Rotational Electrode Misalignment on a Planar Linear Ion Trap Mass Spectrometer

Abstract

The performance of miniaturized ion trap mass analyzers is limited, in part, by the accuracy with which electrodes can be fabricated and positioned relative to each other. Alignment of plates in a two-plate planar LIT is ideal to characterize misalignment effects, as it represents the simplest possible case, having only six degrees of freedom (DOF) (three translational and three rotational). High-precision motorized actuators were used to vary the alignment between the two ion trap plates in five DOFs-x, y, z, pitch, and yaw. A comparison between the experiment and previous simulations shows reasonable agreement. Pitch, or the degree to which the plates are parallel along the axial direction, has the largest and sharpest impact to resolving power, with resolving power dropping noticeably with pitch misalignment of a fraction of a degree. Lateral displacement (x) and yaw (rotation of one plate, but plates remain parallel) both have a strong impact on ion ejection efficiency, but little effect on resolving power. The effects of plate spacing (y-displacement) on both resolving power and ion ejection efficiency are attributable to higher-order terms in the trapping field. Varying the DC (axial) trapping potential can elucidate the effects where more misalignments in more than one DOF affect performance. Implications of these results for miniaturized ion traps are discussed. Graphical Abstract ᅟ.

Mathieu-Hill Equation Stability Analysis for Trapped Ions. Anharmonic Corrections for Nonlinear Electrodynamic Traps

“…An electrodynamic trap is highly susceptible to geometric imperfections and electrode misalignment [44,91,92], that lead to the occurrence of local minima in the trapping potential and nonlinear resonances in the ion dynamics [47,[93][94][95][96]. In case of 2D traps, motional coupling between axial and radial directions is reported [97,98].…”

“…As the technology matures and the trap dimensions continuously scale down, studies are focused on exploring the anharmonic terms of the RF trapping potential for different implementations (geometries) of a quadrupole Paul trap [101,102]. Even if ion traps are intensely investigated both theoretically and experimentally, the effect of small perturbations from ideal conditions due to higher order (multipole) terms of the electric potential, trap asymmetry and geometric imperfections [92,98], along with patch potentials or other perturbing effects, is an issue of high interest. The paper brings new contributions towards this direction.…”

Mathieu–Hill Equation Stability Analysis for Trapped Ions: Anharmonic Corrections for Nonlinear Electrodynamic Traps

“…An electrodynamic (Paul) trap is highly susceptible to geometric imperfections and electrode misalignment [39,93,94], which results in the occurrence of local minima in the trapping electric potential and nonlinear resonances in ion dynamics [42,[95][96][97][98]. In the case of 2D traps, motional coupling between axial and radial directions is reported [99,100].…”

Improving the Performances of a “Brick Mass Spectrometer” by Quadrupole Enhanced Dipolar Resonance Ejection from the Linear Ion Trap

“…A discontinuous atmospheric pressure interface was developed to increase the gas flow rate, while maintaining a low enough pressure in an ion trap. ,, The sinusoidal rf frequency scanning technique was developed to extend the mass range of a Brick mass spectrometer, while working at a relatively low rf voltage . Miniaturized ion traps − and ion trap arrays − have been developed to increase the working pressure of ion traps. New ion trap operation modes were proposed to further simplify a miniature MS system or to improve its quantitation precision. − Even with these advancements, challenges still exist, and the performance of miniature mass spectrometers still needs to be improved to match the increasing demands in practical applications.…”