Applications of the fractional calculus to study the physical theory of ion motion in a quadrupole ion trap

Abstract

In this article, fractional calculus has been applied to study the motion of ions in a three-dimensional radio frequency quadrupole ion trap; we have called this arrangement a fractional quadrupole ion trap. The main purpose of the article is to show that by controlling the fractional parameter of a trapped ion, one can gain a more efficient mass separation. In what follows, we will see that with decreasing the fractional parameter, we can achieve a smaller first stability region. Note that a small stability diagram will result in a good and acceptable mass separation. Various methods can be proposed to obtain a desired ion acceleration with a sufficient accuracy for good mass separation, which is similar to the one obtained by a fractional ion trap. Some of these methods are using the effects of a damping force, a magnetic field or both on the confinement of particles in the quadrupole ion trap. The first stability regions are plotted for all of the aforementioned methods, and simulation results are provided to compare them with those for the fractional case.

Theoretical fractional formulation of a three-dimensional radio frequency ion trap (Paul-trap) for optimum mass separation

“…High resolution, high-mass accuracy and high dynamic range are interesting features of the Orbitrap. [18][19][20] The cylindrical geometry Paul-trap is easier to design and machine with respect to the hyperbolic geometry trap, and that is why it is increasingly attracting interests. 21,22 Experiments show that the cylindrical ion trap has a good resolution so as to perform mass separation of ions.…”

“…Almost any geometry of trap electrodes with ac voltages applied between them, generating a saddle point in the potential, will cater a pseudo-potential minimum in which charged particles can be trapped. 20 All commonly used mass analyzers use electric and magnetic fields to apply force on charged particles. 1,13 This force causes the oscillating particle to move around the equilibrium point due to a fractional parabolic potential as, U a ðx; y; zÞ…”