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A mixed cluster ion beam to enhance the ionization efficiency in molecular secondary ion mass spectrometry
Author(s) -
Wucher Andreas,
Tian Hua,
Winograd Nicholas
Publication year - 2013
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.6793
Subject(s) - chemistry , ion , mass spectrometry , sputtering , ionization , analytical chemistry (journal) , mass spectrum , static secondary ion mass spectrometry , ion source , chemical ionization , cluster (spacecraft) , molecule , secondary ion mass spectrometry , thermal ionization mass spectrometry , thin film , chromatography , nanotechnology , organic chemistry , computer science , programming language , materials science
RATIONALE Chemical modification of a rare gas cluster ion beam (GCIB) to increase the intensity of desorbed molecular ions in secondary ion mass spectrometry experiments relative to the pure Ar cluster. METHODS Doping of the GCIB by mixing small concentration levels (1–3% relative partial pressure) of CH 4 into the Ar gas driving the cluster ion source. RESULTS Mass spectra measured on a trehalose film using the doped GCIB exhibit enhanced molecular ion signals. From depth profiling experiments, the results are shown to arise from an increase in the ionization efficiency of the sputtered molecules rather than a change in the sputtering yield of neutral species. CONCLUSIONS Tuning of the chemistry of mixed clusters is suggested as a general approach to enhancing the ionization probability of sputtered molecules. Copyright © 2013 John Wiley & Sons, Ltd.