Hyperthermal molecular beam source using a non-diaphragm-type small shock tube
We have developed a hyperthermal molecular beam source employing a non-diaphragm-type small shock tube for gas–surface interaction studies. Unlike conventional shock-heated beam sources, the capability of repetitive beam generation without the need for replacing a diaphragm makes our beam source sui...
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Veröffentlicht in: | Review of scientific instruments 2016-10, Vol.87 (10), p.105117-105117 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | We have developed a hyperthermal molecular beam source employing a non-diaphragm-type small shock tube for gas–surface interaction studies. Unlike conventional shock-heated beam sources, the capability of repetitive beam generation without the need for replacing a diaphragm makes our beam source suitable for scattering experiments, which require signal accumulation for a large number of beam pulses. The short duration of shock heating alleviates the usual temperature limit due to the nozzle material, enabling the generation of a molecular beam with higher translational energy or that containing dissociated species. The shock-heated beam is substantially free from surface-contaminating impurities that are pronounced in arc-heated beams. We characterize the properties of nitrogen and oxygen molecular beams using the time-of-flight method. When both the timing of beam extraction and the supply quantity of nitrogen gas are appropriately regulated, our beam source can generate a nitrogen molecular beam with translational energy of approximately 1 eV, which corresponds to the typical activation energy of surface reactions. Furthermore, our beam source can generate an oxygen molecular beam containing dissociated oxygen atoms, which can be a useful probe for surface oxidation. The dissociation fraction along with the translational energy can be adjusted through the supply quantity of oxygen gas. |
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ISSN: | 0034-6748 1089-7623 |
DOI: | 10.1063/1.4964623 |