Potential Paths for the Hydrogen-Bond Relaxing with (H2O)N Cluster Size

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• 作者：Yongli Huang ; Xi Zhang ; Zengsheng Ma ; Guanghui Zhou ; Yinyan Gong ; Chang Q Sun
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：July 23, 2015
• 年：2015
• 卷：119
• 期：29
• 页码：16962-16971
• 全文大小：486K
• ISSN：1932-7455

文摘

Relaxation of the hydrogen bond (O:H鈥揙) between oxygen ions of undercoordinated molecules fascinates the behavior of water nanodroplets and nanobubbles. However, probing such potentials remains yet far from reality. Here we show that the Lagrangian solution (Huang et al. J. Phys. Chem. B 2013, 117, 13639) transforms the observed H鈥揙 bond (x = H) and O:H nonbond (x = L) lengths and their characteristic phonon frequencies (d_x, 蠅_x) (Sun et al. J. Phys. Chem. Lett. 2013, 4, 2565) into their respective force constants and cohesive energies (k_x, E_x), which results in mapping of the potential paths for the O:H鈥揙 bond relaxing with (H₂O)_N cluster size. Results show that molecular undercoordination not only reduces its size (H鈥揙 length d_H) with enhanced H鈥揙 energy from the bulk value of 3.97 to 5.10 eV for a H₂O monomer but also enlarges their separation (O:H distance d_L) with O:H energy reduction from 95 to 35 meV for a dimer. The H鈥揙 energy gain raises the melting point of water skin from the bulk value 273 to 310 K, and the O:H energy loss lowers the freezing temperature of a 1.4 nm sized droplet from the bulk value 258 to 202 K, which indicates droplet size induced dispersion of the quasisolid phase boundaries.