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报告题目:
材料院《材料科学论坛》:Super Fun of H2O
 报告人:
孙长庆 教授
School of EEE, Nanyang Technological University, Singapore
报告时间:
2013-06-17 15:30
报告地点:
清华大学材料院学术报告厅(逸夫技术科学楼2-321)
主办单位:
材料院《材料科学论坛》 联系人:周济 老师 62772975 欢迎广大师生踊跃参加
  简介:

Abstract
Covering 70% of earth’s surface and 70% of weight of our body, H2O is too strange, too anomalous, and too challenge. In this presentation, I will share that an extension of the “ice Rule” of Pauling [1] has enabled us to clarify a number of puzzling issues including the “master-slave segmented hydrogen bond (O:H-O)”, ultra-short-range interactions (O:H van der Walls interaction, H-O exchange interaction, and O--O inter-electron-pair Coulomb repulsion), and forces driving the asymmetric relaxation dynamics in water ice under various conditions [2].
It has been revealed that:
i) Compression shortens-and-stiffens the softer “O:H” bond and lengthens-and-softens the stiffer “H-O” covalent bond through inter-electron-pair Coulomb repulsion, leading to the low compressibility, O:H-O proton symmetrization, phase-transition temperature (TC) depression, softer phonon (<300 cm-1) stiffening and stiffer phonon (>3000 cm-1) softening [3];
ii) Molecular-undercoordination effects oppositely to compression due to the Goldschmidt-Pauling contraction of the H-O covalent bond, resulting in molecular volume expansion, melting point (viscosity) elevation, binding energy entrapment, bonding charge densification and nonbonding lone electron polarization, stiffer phonon stiffening and softer phonon softening of molecule clusters, surface skins, and ultrathin films of water that perform like ice and hydrophobic at the ambient temperature [4];
iii) The disparity of the segmental specific heat discriminates the two parts in responding to cooling, which shortens alternatively the segments in liquid, solid, and transition phase. In the liquid and solid phases, the O:H bond (of lower specific heat) serves as the “master” that contracts largely and meanwhile forces the stiffer H-O bond as “slave” into Coulomb-repulsion-driven slight elongation, causing O--O contraction and the seemingly normal cooling densification of water and ice; at transition, the master-slave swap roles, turning the O--O into freezing elongation and volume expansion [5].

CV
Sun Changqing, received his Ph.D degree in 1996 at Murdoch University, Australia. He has been working on very-low-energy electron diffraction and STM/S analysis of H, C, N, O, and F chemisorption bonding dynamics, size dependence of nanostructures, and the thermo-mechanical behavior of low-dimensional systems with the development of a set of original theoretical, experimental, and numerical approaches including the bond-band-barrier correlation, bond border-length-strength correlation, nonbonding electron polarization, hydrogen bond asymmetric relaxation dynamics, local bond averaging approach, and the zone-resolved photoelectron  spectroscopy.
1. Pauling, L., The structure and entropy of ice and of other crystals with some randomness of atomic arrangement. J. Am. Chem. Soc., 1935. 57: 2680-2684.
2. Huang, Y.L., X. Zhang, Z.S. Ma, G.H. Zhou, and C.Q. Sun, Ultra-short-range interactions in the hydrogen bond of compressed ice. Communicated, 2013.
3. Sun, C.Q., X. Zhang, and W.T. Zheng, Hidden force opposing ice compression. Chem Sci, 2012. 3: 1455-1460.
4. Sun, C.Q., X. Zhang, J. Zhou, Y.L. Huang, Y. Zhou, C., and W.T. Zheng, Density and Stiffness Amomalies of Under-coordinated Water Molecules. arXiv:1210.1638, 2012.
5. Sun, C.Q., X. Zhang, X. Fu, W. Zheng, J.-l. Kuo, Y. Zhou, Z. Shen, and J. Zhou, Density Evolution Dynamics of Water Cooled from 330 to 80 K. arXiv:1210.1634 2012.

 

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