Ion Trap Trace Gas Detection Using Getter Pre-concentration
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Solution Overview
Problem
Trapping mass spectrometers face limitations in detecting trace gas components due to space charge saturation at high pressures, resulting in ion density below detection limits, making it difficult to accurately analyze trace gas components.
Innovation Solution
A method involving ionization of gas species, confinement in an electrostatic potential within an ion trap, and selective sorption/desorption using non-evaporable getters to increase the concentration of specific gas species, followed by AC excitation and detection, enhances the detection limits of trace gas components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ion trap operates at higher pressures to increase ion density, then detection sensitivity improves, but space charge saturation occurs causing ion density to decrease
Solution Approach 1:
The patent applies preliminary action by pre-concentrating specific gas species using non-evaporable getters before ionization and trapping. This selective pre-concentration ensures that when ions are generated and trapped, the desired trace species are already present at sufficient densities for detection, avoiding the need to operate at high pressures that would cause space charge saturation. The getter material selectively adsorbs target molecules from the gas phase before they enter the trap region.
Solution Approach 2:
The patent extracts specific gas species from the mixed gas composition using non-evaporable getters that selectively adsorb target molecules. This extraction concentrates the trace species separately from the bulk gas matrix, allowing detection at low operating pressures. The getters remove interfering background gases while enriching the trace analytes, solving the space charge problem by avoiding high overall ion densities while maintaining sufficient signal for trace detection.
2Measurement precision
If non-evaporable getters are used to concentrate specific gas species, then detection limits improve, but device complexity increases
Solution Approach 1:
The non-evaporable getters serve multiple functions: they act as selective concentrators for trace gas species, function as pump elements to maintain vacuum, and provide a mechanism for selective adsorption and desorption. This multi-functionality reduces the need for separate components for each task, thereby limiting the increase in device complexity while achieving improved detection limits through selective concentration.
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 method effectively increases the concentration of specific gas species within the ion trap, improving the detection limits of trace gas components and enabling more accurate analysis.
Implementation Method 1
selective removal of gas species other than specific gas species by selective sorption of the gas species other than the specific gas species with a non-evaporable getter
Implementation Method 2
selective sorption of the specific gas species with a non-evaporable getter, followed by desorption of the specific gas species from the non-evaporable getter
Implementation Method 3
desorption of the specific gas species from the non-evaporable getter
Implementation Method 4
producing an electrostatic potential in which the specific ion species are confined in the ion trap to trajectories, at natural oscillation frequencies
Implementation Method 5
exciting confined specific ion species with an AC excitation source having an excitation frequency, scanning the excitation frequency of the AC excitation source to eject the specific ion species from the ion trap
Data Source
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AI summary
A method of detecting specific gas species in an ion trap, the specific gas species initially being a trace component of a first low concentration in the volume of gas, includes ionizing the gas including the specific gas species, thereby creating specific ion species. The method further includes producing an electrostatic potential in which the specific ion species are confined in the ion trap to trajectories. The method also includes exciting confined specific ion species with an AC excitation source having an excitation frequency, scanning the excitation frequency of the AC excitation source to eject the specific ion species from the ion trap, and detecting the ejected specific ion species. The method further includes increasing the concentration of the specific ion species within the ion trap relative to the first low concentration prior to scanning the excitation frequency that ejects the ions of the specific gas species.