Ion Trap Double Resonance Ejection for Mass Resolution
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Solution Overview
Problem
Current ion trap systems face limitations in achieving high mass resolution, particularly in quadrupole ion traps, where the mass selective instability scan method is constrained by the fixed instability boundary, limiting the mass/charge range and resolution.
Innovation Solution
The implementation of double resonance ejection methods, which involve generating and applying a combination of fundamental secular frequency and lower sideband frequencies to the ion trap, allowing for arbitrary static or dynamic frequencies, thereby enhancing mass resolution beyond traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass selective instability scan is used with fixed instability boundary, then the method is simple to operate, but mass resolution and mass/charge range are limited
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed instability boundary to a dynamic resonance ejection method. A supplementary AC signal is introduced to create a movable resonance condition that can be scanned across different m/z values, enabling dynamic mass selection and ejection while maintaining operational simplicity through automated frequency scanning.
Solution Approach 2:
The patent changes the operating parameters by introducing a supplementary AC signal with variable frequency and amplitude. By modulating these parameters, the system creates可调 resonance conditions that allow ions of different m/z ratios to be selectively ejected, thereby improving mass resolution without significantly complicating the device operation.
2Measurement precision
If resonance ejection with supplementary AC signal is used, then mass resolution is improved, but the system complexity increases
Solution Approach 1:
The patent achieves universality by designing a system where the supplementary AC signal can serve multiple functions: creating resonance conditions for ejection, enabling mass spectral scanning, and providing selective ion manipulation. This multi-functionality improves ease of operation by consolidating multiple capabilities into a single integrated approach rather than requiring separate systems for each function.
3Ease of operation
If frequency scanning is used instead of amplitude scanning, then instrumentation is simplified, but the mass/charge range coverage is constrained
Solution Approach 1:
The patent applies dimensionality change by utilizing both frequency and amplitude dimensions of the supplementary AC signal. Instead of relying solely on frequency scanning, the system modulates both frequency and amplitude parameters to create a two-dimensional control space, thereby expanding the accessible mass/charge range while maintaining instrumentation simplicity through a unified signal generation approach.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly improves mass resolution, more than tripling it compared to single resonance ejection, and increases versatility by allowing operation at any arbitrary frequency, regardless of the chosen method or frequency.
Implementation Method 1
Ion stability in characteristic dimensions r and z is usually expressed in terms of dimensionless Mathieu parameters a and q. The stability condition can also be expressed in terms of Mathieu β parameters.
Implementation Method 2
A mass spectrum can be recorded by ramping the frequency of the supplementary ac so that resonance is possible with ions of different secular frequencies. This experiment, known as a secular frequency scan, has the practical advantage of not requiring a scan of the main rf amplitude or frequency
Implementation Method 3
The relationship between the ion secular frequency and the Mathieu β parameter is: ωz=βzΩ/2
Data Source
AI summary
The invention generally relates to systems and methods for ejection of ions from an ion trap. In certain embodiments, systems and methods of the invention sum two different frequency signals into a single summed signal that is applied to an ion trap. In other embodiments, an amplitude of a single frequency signal is modulated as the single frequency signal is being applied to the ion trap. In other embodiments, a first alternating current (AC) signal is applied to an ion trap that varies as a function of time, while a constant radio frequency (RF) signal is applied to the ion trap.