Ion traps that apply an inverse Mathieu q scan
The invention generally relates to ion traps and methods of use thereof. In certain embodiments, the invention provides a system that includes a mass spectrometer including an ion trap, and a central processing unit (CPU). The CPU has storage that is coupled to the CPU for storing instructions that when executed by the CPU cause the system to apply a constant radio frequency (RF) signal to the ion trap, and apply a first alternating current (AC) signal to the ion trap the frequency of which varies as a function of time.
1. A system, the system comprising:
a mass spectrometer comprising an ion trap; and
a central processing unit (CPU), and storage coupled to the CPU for storing instructions that when executed by the CPU cause the system to:
apply a constant radio frequency (RF) signal to the ion trap; and
apply an alternating current (AC) signal to the ion trap in a manner wherein frequency and amplitude of the AC signal are varied such that there is an inverse relationship between a Mathieu q parameter corresponding to the applied frequency of the AC signal and time while giving rise to an approximately constant well depth.
2. The system according to claim 1 , wherein the AC signal is in resonance with a secular frequency of ions trapped within the ion trap.
3. The system according to claim 1 , wherein the ion trap is selected from the group consisting of: a hyperbolic ion trap, a cylindrical ion trap, a linear ion trap, a rectilinear ion trap.
4. The system according to claim 1 , wherein the mass spectrometer is a miniature mass spectrometer.
5. The system according to claim 1 , wherein a first detector of the mass spectrometer is positioned orthogonal to the ion trap such that unstable ions are ejected from the ion trap and are received at the first detector.
6. The system according to claim 1 , wherein a first detector of the mass spectrometer is positioned in-line with the ion trap such that stable ions that pass through the ion trap are received at the first detector, and a second detector of the mass spectrometer is positioned orthogonal to the ion trap such that unstable ions ejected from the ion are received at the second detector.
7. The system according to claim 1 , further comprising an ionization source.
8. The system according to claim 1 , further comprising a discontinuous interface.
9. A method for operating an ion trap of a mass spectrometer, the method comprising:
applying a constant radio frequency (RF) signal to an ion trap of a mass spectrometer; and
applying an alternating current (AC) signal to the ion trap in a manner wherein frequency and amplitude of the AC signal are varied such that there is an inverse relationship between a Mathieu q parameter corresponding to the applied frequency of the AC signal and time while giving rise to an approximately constant well depth.
10. The method according to claim 9 , wherein the AC signal is in resonance with a secular frequency of ions trapped within the ion trap.
11. The method according to claim 9 , wherein the ion trap is selected from the group consisting of: a hyperbolic ion trap, a cylindrical ion trap, a linear ion trap, a rectilinear ion trap.
12. The method according to claim 9 , wherein the mass spectrometer is a miniature mass spectrometer.
13. The method according to claim 9 , wherein a first detector of the mass spectrometer is positioned orthogonal with the ion trap such that unstable ions are ejected from the ion trap and are received at the first detector.
14. The method according to claim 9 , wherein a first detector of the mass spectrometer is positioned in-line with the ion trap such that stable ions that pass through the ion trap are received at the first detector, and a second detector of the mass spectrometer is positioned orthogonal to the ion trap such that unstable ions ejected from the ion are received at the second detector.
15. The method according to claim 9 , further comprising detecting ions ejected from the ion trap resulting from application of the AC signal to the ion trap.
16. The method according to claim 9 , wherein ions are discontinuously introduced into the ion trap.