Nested electrostatic linear ion traps and methods of operating the same
Methods and systems for operating an ELIT are provided herein. In accordance with various aspects of the present teachings, and ELIT is provided that can enable simultaneous trapping of two different groups of ions as each group oscillates along a different path length within the ELIT.
1 . An electrostatic linear ion trap (ELIT), comprising:
a first set of electrode plates having holes in the center and aligned along a central axis;
a second set of electrode plates having holes in the center and aligned along the central axis;
one or more voltage sources; and
a controller, operably coupled to the one or more voltage sources, configured to:
apply voltages from the one or more voltage sources to a first group of plates of the first and second sets of electrode plates to cause the first group of plates to trap a first group of ions within a first path length along the central axis; and
simultaneously
apply voltages from the one or more voltage sources to a second group of plates of the first and second sets of electrode plates to cause the second group of plates to trap a second group of ions within a second path length along the central axis, wherein the second path length is longer than the first path length.
2 . The ELIT of claim 1 , wherein the controller is further configured to cause the second group of plates to trap the second group of ions within the second path length while the first group of ions are trapped within the first path length or wherein the controller is further configured to control the injection of the first and second groups of ions into the first and second sets of electrode plates.
3 . The ELIT of claim 1 , wherein the controller is operably coupled to an upstream ion trap from which the first and second groups of ions are injected into the first and second sets of electrode plates.
4 . The ELIT of claim 1 , further comprising at least one detector disposed between the first set of electrode plates and the second set of electrode plates.
5 . The ELIT of claim 4 , wherein the at least one detector is configured to measure the electric current induced by the first group of ions oscillating along the first path length and the electric current induced by the second group of ions oscillating along the second path length.
6 . The ELIT of claim 4 , wherein the at least one detector comprises a first detector configured to measure the electric current induced by the first group of ions oscillating along the first path length and a second detector configured to measure the electric current induced by the second group of ions oscillating along the second path length.
7 . The ELIT of claim 1 , wherein the first group of ions and the second group of ions differ in at least one of polarity and injection energy.
8 . The ELIT of claim 1 , wherein the first group of plates and the second group of plates do not share any plates.
9 . The ELIT of claim 1 , wherein each of the first group of plates and the second group of plates includes at least one trapping plate, at least one plate to change the curvature of the electric field near a turning point, and at least one plate to radially confine ions.
10 . The ELIT of claim 1 , wherein the first group of plates includes at least four plates from the first set and at least four plates from second set and wherein the second group of plates includes at least four plates from the first set and at least four plates from second set.
11 . The ELIT of claim 1 , further comprising one or more switches, wherein the controller is further operably connected to the one or more switches so as to:
select the first path length by applying voltages from the one or more voltage sources to the first set and the second set that cause the first group of plates to trap a third group of ions within the first path length; and
select the second path length by applying voltages from the one or more voltage sources to the first set and the second set that cause the second group of plates to trap the third group of ions within the second path length.
12 . The ELIT of claim 1 , wherein a third group of plates of the first set and the second set are positioned along the central axis to trap ions within a third path length of the central axis that is longer than the second path length.
13 . A method of operating an electrostatic ion trap (ELIT), comprising:
applying voltages from one or more voltage sources to a first group of plates of a first set of electrode plates and a second set of electrode plates, wherein each electrode plate of the first and second sets of electrode plates have a hole in the center aligned along a central axis, wherein the application of voltages causes a first group of ions to be trapped within a first path length along the central axis defined by the first group of plates; and
simultaneously applying voltages from the one or more voltage sources to a second group of plates of the first and second sets of electrode plates to cause the second group of plates to be configured to trap a second group of ions within a second path length along the central axis, wherein the second path length is longer than the first path length.
14 . The method of claim 13 , wherein at least one detector is disposed between the first and second sets of electrode plates, the method further comprising measuring with at least one detector the electric current induced by the first group of ions oscillating along the first path length and the electric current induced by the second group of ions oscillating along the second path length.
15 . The method of claim 13 , further comprising:
measuring with a first detector the electric current induced by the first group of ions oscillating along the first path length; and
measuring with a second detector the electric current induced by the second group of ions oscillating along the second path length.
16 . The method of claim 13 , further comprising trapping the second group of ions within the second path length while the first group of ions are trapped within the first path length.
17 . The method of claim 16 , further comprising detecting a frequency of oscillation of the first group of ions after trapping the second group of ions within the second path length.
18 . The method of claim 13 , further comprising detecting a frequency of oscillation of the first group of ions prior to trapping the second group of ions within the second path length.
19 . The method of claim 13 , wherein the first group of ions and the second group of ions differ in at least one of polarity and injection energy.
20 . A computer program product, comprising a non-transitory and tangible computer-readable storage medium whose contents include a program with instructions being executed on a processor to perform the method of claim 13 .