Proton order in the ice crystal surface
Proton order in the ice crystal surface
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DOI：
10.1073/pnas.0710129105
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发表时间：
2008-04-22
影响因子：
11.1
通讯作者：
Tosatti, E.
中科院分区：
文献类型：
--
作者：
Buch, V.;Groenzin, H.;Tosatti, E.
冰晶表面的物理学及其与吸附物的相互作用不仅是地球和行星化学的基本兴趣，而且是相当重要的。然而，即使是原始冰面在低温下的原子级结构也远未得到很好的理解。这项计算研究的重点是悬挂H和悬挂0（孤对）原子在基底冰面的图案。悬挂原子作为吸附物的结合位点，能够形成氢键和静电键。著名的取向无序的延伸（“质子无序”）的大块晶体冰的表面将自然地提出一个无序的悬挂原子模式;然而，如弗莱彻[弗莱彻NH（1992）Philos Mag 66：109-115]。基底表面内条纹相域的存在与10年前观察到的氦衍射图案中迄今无法解释的次要分数峰是一致的。与无序模型相比，条纹模型产生更好的一致性之间的计算和实验PPP极化和频产生谱。
The physics of the ice crystal surface and its interaction with adsorbates are not only of fundamental interest but also of considerable importance to terrestrial and planetary chemistry. Yet the atomic-level structure of even the pristine ice surface at low temperature is still far from well understood. This computational study focuses on the pattern of dangling H and dangling 0 (lone pairs) atoms at the basal ice surface. Dangling atoms serve as binding sites for adsorbates capable of hydrogen-and electrostatic bonding. Extension of the well known orientational disorder ("proton disorder") of bulk crystal ice to the surface would naturally suggest a disordered dangling atom pattern; however, extensive computer simulations employing two different empirical potentials indicate significant free energy preference for a striped phase with alternating rows of dangling H and dangling 0 atoms, as suggested long ago by Fletcher [Fletcher NH (1992) Philos Mag 66:109-115]. The presence of striped phase domains within the basal surface is consistent with the hitherto unexplained minor fractional peaks in the helium diffraction pattern observed 10 years ago. Compared with the disordered model, the striped model yields improved agreement between computations and experimental ppp-polarized sum frequency generation spectra.