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Influence of laser focusing in matrix‐assisted laser desorption/ionization
Author(s) -
Riahi Karim,
Bolbach Gérard,
Brunot Alain,
Breton Francis,
Spiro Marenglen,
Blais JeanClaude
Publication year - 1994
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290080304
Subject(s) - chemistry , laser , fluence , metastability , ion , ionization , atomic physics , atmospheric pressure laser ionization , matrix assisted laser desorption electrospray ionization , soft laser desorption , desorption , matrix assisted laser desorption/ionization , optics , electron ionization , physics , organic chemistry , adsorption
The influence of laser focusing on the target in matrix‐assisted laser desorption/ionization (MALDI) has been studied. The emission of stable and metastable molecular ions of bovine insulin depends on both the laser energy and the distance between the target and the laser focal plane. The results clearly show that the laser fluence is the important parameter in MALDI. The fluence threshold of metastable‐ion emission is higher than that of stable‐ion emission. Beyond this threshold, the emission of stable ions reaches a plateau. This is due to the spatial inhomogeneity of the laser energy distribution. A phenomenological model including two fluence thresholds for the stable‐ and metastable‐ion emission has been developed and compared to the experimental data.