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Determination of atomic hydrogen in non‐thermal hydrogen plasmas by means of molecular beam threshold ionization mass spectrometry
Author(s) -
Wang WeiGuo,
Xu Yong,
Yang XueFeng,
Wang WenChun,
Zhu AiMin
Publication year - 2005
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.1906
Subject(s) - chemistry , hydrogen , mass spectrometry , analytical chemistry (journal) , ionization , molecular beam , electron ionization , atomic physics , thermal ionization , ion source , mass spectrum , dissociation (chemistry) , ion , molecule , physics , organic chemistry , chromatography
Atomic hydrogen plays important roles in chemical vapor deposition of functional materials, plasma etching and new approaches to chemical synthesis of hydrogen‐containing compounds. The present work reports experimental determinations of atomic hydrogen near the grounded electrode in medium‐pressure dielectric barrier discharge hydrogen plasmas by means of molecular beam threshold ionization mass spectrometry (MB‐TIMS). At certain discharge conditions (a.c. frequency of 24 kHz, 28 kV of peak‐to‐peak voltage), the measured hydrogen dissociation fraction is decreased from ∼0.83% to ∼0.14% as the hydrogen pressure increases from 2.0 to 14.0 Torr. A simulation method for extraction of the approximate electron beam energy distribution function in the mass spectrometer ionizer and a semi‐quantitative approach to calibrate the mass discrimination effect caused by the supersonic beam formation and the mass spectrometer measurement are reported. Copyright © 2005 John Wiley & Sons, Ltd.