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 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.
Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Yuta
Y
Yoshimoto
Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Kenichi
K
Osuka
Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Nobuya
N
Miyoshi
Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Ikuya
I
Kinefuchi
Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Shu
S
Takagi
Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Yoichiro
Y
Matsumoto