Multi-Reflection TOF Ion Mirror Surface Patch Potential Control
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Solution Overview
Problem
Time-of-flight mass spectrometers face limitations in resolving power and ion transmission due to ion optical properties of ion mirrors, particularly in multiple-reflection systems, where ion beam divergence and surface patch potentials cause de-focusing and performance issues.
Innovation Solution
A method and apparatus that utilize collimated ion beams and surfaces with reduced surface patch potentials, achieved through coatings or heating, to maintain low divergence and prevent beam divergence during multiple reflections, eliminating the need for complex periodic focusing lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple reflections between two coaxial ion mirrors are used to improve resolving power, then the ion path length increases, but the mass range is limited due to overlap of ions of different mass-to-charge ratio
Solution Approach 1:
The patent employs mirrors with different orientations (one mirror at normal incidence, another at oblique incidence) to create asymmetric ion trajectories. This asymmetric path geometry allows ions of different mass-to-charge ratios to follow distinct reflection patterns, preventing overlap and enabling extended mass range analysis while maintaining high resolving power through multiple reflections.
2Length of moving object
If ion mirrors with large angle of incidence are used to achieve multiple reflections, then the ion path length increases, but the system complexity increases
Solution Approach 1:
The ion mirror system is segmented into distinct functional zones: a first mirror handling normal incidence reflections and a second mirror handling oblique incidence reflections. This segmentation allows each mirror to be optimized for its specific function, simplifying the overall design while achieving the required ion path length through coordinated operation of the segmented mirror assembly.
3Stability of the object's composition
If additional planar lenses are positioned between opposing elongated mirrors to focus the ion beam, then the ion beam divergence is reduced, but the device complexity and implementation difficulty increase
Solution Approach 1:
The patent extracts the focusing function from separate lens components and integrates it into the mirror surfaces themselves. By coating the mirror surfaces with conductive materials and applying appropriate voltages, the mirrors themselves provide the electrostatic focusing needed to control ion beam divergence, eliminating the need for additional lens components and simplifying the overall device architecture.
4Ease of manufacture
If conventional ion mirrors are used without surface treatment, then the mirror design is simple, but surface patch potentials cause de-focusing and reduce transmission
Solution Approach 1:
The patent modifies the surface properties of the ion mirrors by applying conductive coatings (such as gold, silver, or aluminum) and controlling surface potential parameters through voltage application. These parameter changes eliminate surface patch potential effects that cause de-focusing, thereby improving ion transmission and reliability while maintaining relatively simple mirror geometries that are easy to manufacture.
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 enables high-resolution time-of-flight mass spectrometry with low divergence ion beams, enhancing the performance and sensitivity of multi-reflection TOF systems by minimizing surface patch potential variations, thus achieving high-resolution analysis without the complexity and cost of additional focusing lenses.
Implementation Method 1
providing a coating on and/or heating the one or more surfaces to reduce the variation in their surface patch potentials
Implementation Method 2
providing a coating on and/or heating the one or more surfaces to reduce the variation in their surface patch potentials
Implementation Method 3
Time of flight (TOF) mass spectrometers are widely used to determine the mass-to-charge ratio (m/z) of ions on the basis of their flight time along a flight path
Implementation Method 4
multiple-reflection TOF (MR TOF) systems employing ion mirrors are known as one of the ways to improve resolving power without increasing greatly the size of an instrument
Data Source
AI summary
A method for analyzing ions according to their mass-to-charge ratio and mass spectrometer for performing the method, comprising directing a collimated ion beam along an ion path from an ion source to an ion detector, causing a portion of the ion beam to contact one or more surfaces prior to reaching the ion detector, wherein the method comprises providing a coating on and/or heating the one or more surfaces to reduce variation in their surface patch potentials. The method is applicable to multi-reflection time-of-flight (MR TOF) mass spectrometry.