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Laser desorption/ablation plumes from capillary-like restricted volumes
1Novartis Institutes for Biomedical Research, WSJ 503.1104, 4052 Basel, Switzerland. rknochenmuss@gmx.net
Summary
Structured surfaces in laser desorption/ionization (LDI) affect ion plume conditions. Capillary nozzle modeling reveals more primary ions but fewer analyte ions due to altered plume chemistry in LDI.
Area of Science:
- Analytical Chemistry
- Surface Science
- Mass Spectrometry
Background:
- Laser desorption/ionization (LDI) from structured surfaces is gaining attention.
- Plume conditions in LDI from structured surfaces differ from bulk ablation.
- Recombination and secondary ion-molecule reactions in the plume are critical for ion detection.
Purpose of the Study:
- To model the plume dynamics of LDI from structured surfaces.
- To investigate the impact of structured surfaces on ion generation and detection.
- To adapt existing LDI models for free jet expansion from capillary orifices.
Main Methods:
- Modeling desorption/ionization substrates with high aspect ratio channels as capillary nozzles.
- Adapting a previously developed matrix-assisted laser desorption/ionization (MALDI) ablation/ionization model for free jets.
- Analyzing ion yields based on plume conditions and secondary reactions.
Main Results:
- Ablation from capillary orifices increases the number of primary ions reaching the detector.
- Fewer analyte ions are formed in secondary reactions within the plume from capillary orifices.
- Ion yield differences persist in arrays of capillaries, influenced by diameter-to-spacing ratios.
Conclusions:
- Structured surfaces significantly alter LDI plume chemistry and ion formation.
- Capillary nozzle modeling provides insights into ion generation from structured LDI substrates.
- Optimizing surface structure is crucial for enhancing ion detection in LDI applications.
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