Conversion Dynode Material for Sensitive Negative Ion Detection
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Solution Overview
Problem
Conventional ion detectors using conversion dynodes and secondary electron multiplier tubes struggle to quantify negative ions, such as PFAS and haloacetic acids, with high sensitivity due to lower emission of secondary particles when primary ions are negative.
Innovation Solution
The conversion dynode surface, including the ion collision surface, is made of a substance containing titanium, vanadium, or chromium at a higher density than iron or aluminum, allowing for increased secondary ion emission regardless of ion polarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional conversion dynode materials (iron or aluminum) are used, then the device structure is simple and manufacturing is easy, but the detection sensitivity for negative ions is low
Solution Approach 1:
The invention changes the material parameter of the conversion dynode surface from conventional iron or aluminum to titanium, vanadium, or chromium. This material substitution fundamentally alters the secondary particle emission characteristics, enabling high detection sensitivity for both positive and negative ions while maintaining manufacturing feasibility through standard deposition techniques
Solution Approach 2:
The invention creates a composite structure where a layer of titanium, vanadium, or chromium is formed on the conversion dynode surface. This composite material approach combines the beneficial properties of the base material with the superior ion emission properties of the surface layer, achieving enhanced detection sensitivity without completely replacing the original dynode structure
2Measurement precision
If the conversion dynode surface is made of titanium, vanadium, or chromium, then the detection sensitivity for negative ions is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The invention applies local quality by forming titanium, vanadium, or chromium specifically on the ion collision surface of the conversion dynode where secondary particle emission is most critical. This localized treatment ensures high detection sensitivity where needed while keeping other parts of the device relatively simple
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 configuration enables high-sensitivity quantification of both positive and negative ions, particularly improving detection sensitivity for components like PFAS and haloacetic acids.
Implementation Method 1
A conversion dynode emits secondary particles having a charge of opposite polarity to the primary ions when primary ions, which are the ions to be detected, collide with it.
Implementation Method 2
A secondary electron multiplier tube has a plurality of dynodes connected, and when an ion or electron collides with the first dynode, multiple electrons are emitted. When each of these multiple electrons collides with the second dynode, multiple electrons are further emitted, and by repeating this operation, a large number of electrons are generated.
Implementation Method 3
a DC voltage of an appropriate magnitude according to the polarity of the primary ions to be detected is applied between the conversion dynode and the secondary electron multiplier tube. As a result, a force is applied to the primary ions toward the conversion dynode side. Then, the primary ions are accelerated by the DC voltage and collide with the conversion dynode, and the secondary particles emitted thereby are accelerated by the DC voltage in the opposite direction to the primary ions and enter the secondary electron multiplier tube.
Data Source
AI summary
An ion detector (24) comprises a conversion dynode (241), a secondary electron multiplier tube (242), and a DC voltage application unit (243) that applies a DC voltage between the conversion dynode (241) and the secondary electron multiplier tube (242). A part or all of a surface of the conversion dynode (241), including an ion collision surface (2410) where ions collide, is made of a substance containing one or more elements selected from the group consisting of titanium, vanadium, and chromium at a higher density than iron and aluminum.