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A resistive pyrolytic radical source for gas-surface reaction studies
David Y Lee1, Matthew M Jobbins, S Alex Kandel
1Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
The Review of Scientific Instruments
|May 8, 2012
Summary
We developed a new thermal gas cracker using inert graphite for radical generation in surface reaction studies. This instrument efficiently produces chlorine atoms from chlorine gas, achieving high conversion rates at elevated temperatures.
Area of Science:
- Chemical Physics
- Materials Science
- Surface Science
Background:
- Radical-surface reactions are crucial in various scientific fields.
- Producing controlled fluxes of gas-phase radicals is essential for studying these reactions.
- Existing methods for radical generation may have limitations in terms of inertness or efficiency.
Purpose of the Study:
- To design and characterize a novel thermal gas cracker for generating low fluxes of gas-phase radicals.
- To utilize a highly oriented pyrolytic graphite filament for enhanced thermal stability and inertness.
- To demonstrate the instrument's effectiveness in producing chlorine atoms from chlorine gas.
Main Methods:
- A resistively heated, highly oriented pyrolytic graphite filament was used as the pyrolysis source.
- The cracker was integrated into a titanium sublimation pump for self-pumping capabilities.
- Chlorine gas (Cl2) was used to generate chlorine atoms (Cl), and the process was monitored using a residual gas analyzer.
Main Results:
- The thermal gas cracker successfully produced chlorine atoms from chlorine gas.
- Monitoring confirmed the generation of (35)Cl and (37)Cl isotopes with a decrease in parent (70)Cl2 and (72)Cl2.
- The cracking fraction of Cl2 was quantified as a function of cell temperature, showing nearly complete conversion at high temperatures.
Conclusions:
- The developed thermal gas cracker is effective for producing gas-phase radicals.
- The use of pyrolytic graphite offers an inert and stable platform for radical generation.
- The instrument is suitable for applications in radical-surface reaction studies.
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