1. Atomic hydrogen determination in medium-pressure microwave discharge hydrogen plasmas via emission actinometry
- Author
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Xue-Feng Yang, Zi-Cai Geng, Wei-Guo Wang, Ai-Min Zhu, and Yong Xu
- Subjects
Actinometer ,Plasma etching ,Hydrogen ,Analytical chemistry ,chemistry.chemical_element ,Balmer series ,Condensed Matter Physics ,Dissociation (chemistry) ,law.invention ,symbols.namesake ,chemistry ,law ,symbols ,Light emission ,Physics::Atomic Physics ,Emission spectrum ,Atomic physics ,Microwave - Abstract
Atomic hydrogen plays an important role in the chemical vapour deposition of functional materials, plasma etching and new approaches to the chemical synthesis of hydrogen-containing compounds. This work reports experimental determinations of atomic hydrogen in microwave discharge hydrogen plasmas formed from the TM01 microwave mode in an ASTeX-type reactor, via optical emission spectroscopy using Ar as an actinometer. The relative intensities of the H atom Balmer lines and Ar-750.4 nm emissions as functions of input power and gas pressure have been investigated. At an input microwave power density of 13.5 W cm−3, the approximate hydrogen dissociation fractions calculated from electron-impact excitation and quenching cross sections in the literature, decreased from ~0.08 to ~0.03 as the gas pressure was increased from 5 to 25 Torr. The influences of the above cross sections, and the electron and gas temperatures of the plasmas on the determination of the hydrogen dissociation fraction data have been discussed.
- Published
- 2005
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