MSI’s Resolution-Fragmentation Trade-Off

Researchers map the physical forces shaping impingement-based mass spectrometry imaging

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A physics-based framework classifies MSI extraction as thermodynamic desorption, kinematic extraction, or a mixture of both.
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The dimensionless parameter Πσ compares impact-generated stress with the cohesive forces binding molecules to the sample; kinematic extraction can begin at Πσ ≥ 1.
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The model indicates that active extraction requires electric acceleration to exceed the combined effects of aerodynamic drag and inertia.
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The framework places atmospheric-pressure DESI, nano-DESI, and liquid microjunction sampling mainly in the thermodynamic regime, and vacuum-based droplet-impact and cluster-ion methods mainly in the k
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Higher Πσ values are associated with greater fragmentation likelihood, but Πσ does not directly predict ionization softness.

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