Photo-ionisation in RF Ion Traps for Reagent Ion Generation
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Solution Overview
Problem
Conventional mass spectrometers face limitations in generating a high concentration of reagent ions and excited species within the RF ion guide or ion trap, which hinders efficient ion-ion, ion-molecule, and ion-excited neutral reactions, particularly in fragmenting singly charged analyte ions and altering their charge state.
Innovation Solution
The mass spectrometer incorporates a photo-ionisation device, such as a UV lamp, to ionize a reagent gas within the RF ion guide or ion trap, generating reagent ions that interact with neutral molecules to fragment and dissociate analyte ions, and control the residence time of ions using transient DC potentials, enabling efficient ion-ion, ion-molecule, or ion-excited neutral reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If reagent ions are produced remotely and transferred to the reaction region, then the ion source can be separated from the reaction chamber, but the concentration of reagent ions within the RF ion guide or ion trap is insufficient for efficient ion-ion and ion-molecule reactions
Solution Approach 1:
The patent merges the ion source function with the RF ion guide or ion trap by introducing a photo-ionisation device directly into the reaction chamber. This allows reagent gas to be ionized in situ within the confined ion region, achieving high reagent ion concentration without requiring separate ion source and reaction chamber components.
Solution Approach 2:
The patent introduces a photo-ionisation device as an intermediary component that enables direct ionization of reagent gas within the RF ion guide or ion trap. This mediator allows efficient energy transfer from photons to reagent molecules, producing high concentrations of reagent ions without complex transfer mechanisms.
2Productivity
If conventional remote ion production is used, then device structure is simpler, but ion-ion and ion-molecule reaction efficiency is reduced
Solution Approach 1:
The patent applies preliminary action by ionizing the reagent gas before it enters the reaction with analyte ions. The photo-ionisation device pre-creates reagent ions within the RF ion guide or ion trap, ensuring high reaction efficiency when analyte ions are introduced without requiring complex post-ionization mechanisms.
Solution Approach 2:
The patent utilizes periodic action through the RF (radio frequency) field that confines and repeatedly accelerates ions within the ion guide or trap. This periodic electromagnetic field enhances ion-molecule collision frequency and reaction efficiency while maintaining a compact device structure.
3Quantity of substance
If reagent ions are generated within the RF ion guide or ion trap, then high concentration of reactive species is achieved, but additional photo-ionisation equipment is required
Solution Approach 1:
The photo-ionisation device serves multiple functions: it ionizes reagent gas to produce reagent ions, excites reagent molecules to create excited species, and can be integrated with the existing vacuum and RF systems. This multi-functionality justifies the added equipment by eliminating the need for separate ion sources and transfer mechanisms.
Solution Approach 2:
The system achieves self-service by using the photo-ionisation device to automatically generate both reagent ions and excited species within the reaction chamber. The RF field and photo-ionisation work together to maintain optimal reaction conditions without requiring external intervention or complex control systems.
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 allows for high-probability interactions between reagent ions and neutral molecules, effectively fragmenting singly charged analyte ions and altering their charge state, enhancing the analytical capabilities of mass spectrometry.
Implementation Method 1
a photo-ionisation device, such as a UV lamp, to ionize a reagent gas within the RF ion guide or ion trap
Implementation Method 2
The reagent and dopant ions react with analyte molecules by charge exchange or proton transfer to produce analyte ions
Implementation Method 3
The reagent and dopant ions react with analyte molecules by charge exchange or proton transfer to produce analyte ions
Implementation Method 4
ion-ion reactions or ion-radical reactions such as Electron Transfer Dissociation ('ETD') are performed within an RF ion guide or ion trap
Implementation Method 5
control the residence time of ions using transient DC potentials
Data Source
Figure 1
AI summary
A mass spectrometer is disclosed comprising an RF ion guide or ion trap and a device arranged and adapted to supply a reagent gas within the RF ion guide or ion trap. The mass spectrometer further comprises a photo-ionisation device and a control system arranged and adapted: (i) to cause first ions to fragment or dissociate within the RF ion guide or ion trap to form second ions and neutral molecules; and (ii) to cause the photo- ionisation device to photo-ionise and/or photo-excite the reagent gas to form reagent ions, excited species or radical species. The reagent ions, excited species or radical species interact with at least some of the neutral molecules located within the RF ion guide or ion trap to form analyte ions.