Посилання:Electron attachment to atomic hydrogen on the surface
of liquid ⁴He / T. Arai, H. Yayama, K. Kono // Физика низких температур. — 2008. — Т. 34, № 4-5. — С. 496–503. — Бібліогр.: 28 назв. — англ.
Підтримка:This work has been supported by President’s Special Research Grant of RIKEN, Grant-in-Aid for Scientific Research (B) from JSPS and Grant-in-Aid for Exploratory Research from MEXT. We thank T. Shiino and T. Mitsui for partial collaboration. We are grateful to A. Wrl and P. Leiderer for VCE installation and valuable discussions. We are grateful to T. Kumada for informing us the charge-induced dipole interaction. This work was carried out under the Joint Research Program of the Institute for Solid State Physics, University of Tokyo.
We demonstrate a possibility that helium surface electrons at cryogenic temperatures can be used as a
new source of very low energy electrons. Since both electrons (e¯) and hydrogen atoms (H) are bound on liquid
helium surface, two-dimensional mixture gas of these two species is available on the surface. We found
that low energy collision of e¯ and H drives electron attachment to form a negative hydrogen ion (H¯) in the
mixture. From our temperature dependence measurement of the reaction rate, it was found that another H
atom participate in the reaction. Namely, the reaction is expressed as H + H + e¯ → H¯ + H. Possible reaction
mechanisms are discussed in terms of direct three-body process and dissociative attachment process. Measurements
in applied magnetic field (B) show that the reaction rate coefficient is suppressed as ~ B⁻². This
implies that electron spin singlet collision is relevant for electron attachment.