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Secondary effects in laser ionization surface analysis
Author(s) -
Rohr K.,
Thoemmes R.
Publication year - 1990
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740150104
Subject(s) - laser , atomic physics , ion , ionization , chemistry , bremsstrahlung , kinetic energy , substrate (aquarium) , thermal ionization , tantalum , desorption , soft laser desorption , plasma , analytical chemistry (journal) , electron ionization , electron , optics , adsorption , matrix assisted laser desorption/ionization , physics , oceanography , organic chemistry , quantum mechanics , chromatography , geology
Contaminated tantalum surfaces have been analysed by a modified laser ionization mass analysis (LIMA) technique in order to investigate the reliability of this method in a situation where the ion yield is optimum. The laser was an Nd‐YAG Q‐switch system (λ = 1.06 μm) of τ = 20 ns pulse length delivering an energy of 0.3 J in the TEM 00 mode. Ions desorbed from the surface and the substrate have been analysed according to their mass and charge and their kinetic energy distribution. The results strongly suggest that the effective region of the surface desorption can be one order of magnitude larger than the geometrical focal region of the laser beam where the substrate particles are desorbed. The effect is explained by secondary Bremsstrahlung interaction. Generally, this imposes severe restrictions on the reliability of quantitative spatially resolved surface analysis techniques where laser‐induced high‐temperature plasmas are present.