@article { ISI:000327460100005,
	title = {Can the Effective Potential of a Linear Quadrupole be Extended to Values of the Mathieu Parameter q Up to 0.90?},
	journal = {JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY},
	volume = {24},
	number = {12},
	year = {2013},
	month = {DEC},
	pages = {1848-1852},
	abstract = {The motion of ions in a linear quadrupole is usually described by solutions to the Mathieu equation. A simplifying approximation to this theory that is widely used for low values of the Mathieu parameters a and q describes ion motion in an effective potential. In this work, we have calculated the effective potential for any q from displacements of calculated ion trajectories caused by a dipole DC electric field. It is assumed that the dipole DC electric field at the center of the displaced trajectory is countered by an {\textquoteleft}{\textquoteleft}effective{{\textquoteright}{\textquoteright}} electric field. For all q values, the effective electric field is found to increase linearly with the distance from the center of the quadrupole. The trapping forces probed in this way increase continuously with q up to the first stability region boundary at q=0.908. The well depth (D) at any q can be described by , where c=3.955 +/- 0.005, very similar to the standard effective potential model with c=4.000.},
	issn = {1044-0305},
	doi = {10.1007/s13361-013-0738-2},
	author = {Gao, Cong and Douglas, D. J.}
}
