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First Observation of Tunneling Diffusion of Hydrogen Atoms on the Surface of Very-Low-Temperature Water Ice

Research Press Release | October 06, 2015

  • Experimental equipment developed at the Institute of Low Temperature Science and used in the present research.
    Experimental equipment developed at the Institute of Low Temperature Science and used in the present research.
  • Conceptual diagram that models how hydrogen atoms move on the surface of microparticles of water ice by a repetition of tunneling diffusion and the usual thermal diffusion, to encounter reaction partners. The light blue wavy line is the ice surface. The red circles are hydrogen atoms, the dashed blue lines are tunneling diffusion, and the solid blue lines are the usual diffusion.
    Conceptual diagram that models how hydrogen atoms move on the surface of microparticles of water ice by a repetition of tunneling diffusion and the usual thermal diffusion, to encounter reaction partners. The light blue wavy line is the ice surface. The red circles are hydrogen atoms, the dashed blue lines are tunneling diffusion, and the solid blue lines are the usual diffusion.
Press Release
Key Points ・First demonstration of tunneling diffusion of hydrogen atoms on the surface of very-low-temperature water ice.

・Clarification of the behavior of hydrogen atoms on the surface of water ice microparticles floating in space.

・Establishment of a new experimental method for comparing the diffusion rates of deuterium atoms and hydrogen atoms.
Overview It is believed that, on microparticles of water ice floating in space, hydrogen atoms that have adhered in the vacuum move around on the surface of the ice and collide with other atoms and molecules to form a variety of molecules, including organic molecules. It has been theoretically predicted that, in the very-low-temperature environment of space, hydrogen atoms move around much faster than usual on the ice surface (tunneling diffusion), as a result of the quantum tunneling effect that is unique to very low temperatures (the phenomenon whereby the wave nature of particles becomes prominent and they can go through energy barriers). However, due to the experimental difficulty, research to demonstrate this has not been performed. By using a novel method, the present research has succeeded for the first time in experimentally observing this tunneling diffusion.
Inquiries

Naoki WATANABE, Institute of Low Temperature Science, Hokkaido University

TEL: +81-11-706-5501

FAX: +81-11-706-7142

E-mail: watanabe@lowtem.hokudai.ac.jp

Japanese

Link

  極低温氷表面での水素原子トンネル拡散を初めて観測  (2015.9.24)
Publications  Signatures of quantum-tunneling diffusion of hydrogen atoms on water ice at 10 K, Physical Review Letters (American Physical Society) (2015.9.23)

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