Title

Ice Surface: Insights from Recent Study

Date: 26 June 2015
Speaker: 王恩哥教授
Professor Wang Enge

Abstract

Despite ice being a ubiquitous and well-studied substance, it is surprising that some basic questions about its surface properties are still debated. Here the recent study of the unusual structure and dynamics of ice surface is discussed at atomic scale. An order parameter, which defines the ice surface energy, is identified for the first time. A classical electrostatic model proves useful to explain the physics inside. We predict that the proton order-disorder transition, which occurs in the bulk at ~72 K, will not occur at the surface at any temperature below surface melting. In addition, it is found that vacancy energy to be as low as ~0.1eV at the surface, leading to a higher than expected concentration of vacancies at the external layer. Once a surface vacancy is formed, the energetic cost of forming neighbouring vacancies is greatly reduced, facilitating pits on the surface and other processes that may contribute to the phenomenon of pre-melting and quasi-liquid layer formation. Finally, we show that the distribution of local arrangement of dangling atoms is of crucial importance for the adsorption of water monomer on ice surface. The positive correlation of adsorption energy of water monomer with surface proton ordering suggests that the adsorption may prefer to firstly occur in the inhomogeneous surface, which sheds light on our understanding of the ice nucleation and growth as well as other physical/chemical reactivity in high altitude clouds.

Speaker Bio

王恩哥教授
Professor Wang Enge

中國科學院副院長
北京大學物理學院講席教授
Vice President of the Chinese Academy of Sciences
Chair Professor of Physics, Peking University

王恩哥教授,中國著名物理學家,中國科學院院士,發展中國家科學院院士,美國物理學會會士,英國物理學會會士。

王教授為現任中國科學院副院長,北京大學講席教授。曾任中國科學院物理研究所所長,北京凝聚態物理國家實驗室主任;北京大學教務長、常務副校長;並於2013至2015年間任北京大學校長。

王教授主要從事凝聚態物理研究,在輕元素納米新材料探索及其物理性質,原子尺度上的表面生長動力學,受限系統中水的行為與特性等方面做出了有重要影響的工作。王教授曾於國際學術期刊上發表300餘篇學術論文,在國際學術會議上做邀請報告80餘次,並擔任多個國際學術期刊執行主編、副主編或編委。於2002至2005年間任國際純粹與應用物理聯合會(IUPAP)專業委員會副主任。

王教授曾獲德國洪堡研究獎、發展中國家科學院物理獎、世界華人物理學會「亞洲成就獎」、亞洲計算材料科學成就獎、陳嘉庚數理科學獎、何梁何利科技進步獎、國家自然科學獎(二等獎)2次、美國史丹福大學“GCEP”訪問學者稱號、日本東北大學“JSPS”訪問教授稱號等。

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