Mass Spectrometer Ion Ejection Control via Potential Slope
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Solution Overview
Problem
Conventional mass spectrometers face challenges in controlling the ejection time of ions from a collisional-damping chamber, leading to inefficient ion utilization, mixing of different ion information, and detector saturation, which affects sensitivity and resolution.
Innovation Solution
A mass spectrometer design that uses a collisional-damping chamber with linear quadrupole electrodes and auxiliary electrodes to apply a radio frequency voltage and DC voltage, allowing for real-time control of ion ejection time by forming a potential slope on the center axis, ensuring ions are ejected uniformly and within the detection limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ions are ejected massively from an ion trap in a very short time, then ion accumulation efficiency is improved, but the time-of-flight mass spectrometer cannot measure those ions efficiently due to detector saturation and ion mixing
Solution Approach 1:
The collisional-damping chamber is positioned between the ion trap and time-of-flight mass spectrometer to preliminarily dampen the ion beam before measurement. Bath gas molecules in the chamber collide with ions, reducing their kinetic energy spread and temporal concentration, thereby preventing detector saturation while maintaining ion accumulation efficiency
Solution Approach 2:
Bath gas molecules serve as an intermediary medium in the collisional-damping chamber. These gas molecules interact with the ion beam through collisions, transferring momentum and energy to spread out the temporal distribution of ions without requiring direct modification of the ion trap or mass spectrometer operation
2Measurement precision
If the ejection time of ions is lengthened to improve measurement efficiency, then detector saturation is prevented, but ion information from different time points mixes together
Solution Approach 1:
The collisional-damping chamber modifies the kinetic energy parameter of ions through controlled collisions with bath gas molecules. This parameter change spreads the temporal distribution of ions, allowing efficient measurement while maintaining information separation through the damping effect that prevents excessive temporal spreading
3Measurement precision
If the amount of bath gas in the collisional-damping chamber is increased to lengthen ion ejection time, then measurement efficiency improves, but sensitivity and resolution may be lowered
Solution Approach 1:
The collisional-damping chamber applies a partial damping effect using a controlled, moderate amount of bath gas rather than excessive gas density. This partial action is sufficient to spread ion temporal distribution and improve measurement efficiency while maintaining sensitivity and resolution by avoiding over-damping that would excessive broadening of ion signals
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 efficient ion measurement by uniformly controlling ejection times, preventing ion mixing and detector saturation, thus enhancing sensitivity and resolution while optimizing ion utilization.
Implementation Method 1
ions that are over a certain mass level come to be stabilized in a quadrupole ion trap, thereby ions can be accumulated therein. If a radio frequency voltage of 1 MHz or so is applied to a ring electrode or cylindrical electrode
Implementation Method 2
a collisional-damping chamber to lengthen the time distribution of ions that have been ejected massively from an ion trap in a short time
Implementation Method 3
a multipole rod electrode disposed in an ion dissociation device is inclined or an inclined electrode is inserted between multipole rod electrodes to generate a DC electric field on the center axis of the multipole electrode in the exit direction, thereby shortening the ejection time of ions
Data Source
AI summary
A mass spectrometer includes a linear multipole electrode, an auxiliary electrode that applies a DC potential on the center axis of the linear multipole electrode, and a DC power supply that supplies a DC power to the auxiliary electrode. The DC potential slope formed on the center axis of the multipole electrode is changed according to the measuring condition. The ejection time of ions can be adjusted optimally by adjusting the potential slope so as to satisfy the measuring condition. If the ejection time of ions is shortened, confusion of different ion information items that might otherwise occur on a spectrum can be avoided. If the ejection time of ions is lengthened, detection limit exceeding can be avoided and ions can be measured efficiently, thereby highly efficient ion measurements are always assured.