1. Nanobubble Skin Supersolidity.
- Author
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Xi Zhang, Xinjuan Liu, Yuan Zhong, Zhaofeng Zhou, Yongli Huang, and Sun, Chang Q.
- Subjects
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NANOSTRUCTURED materials , *MECHANICAL behavior of materials , *RAMAN spectroscopy , *QUANTUM theory , *MOLECULAR dynamics - Abstract
Water nanobubbles manifest fascinatingly higher mechanical strength, higher thermal stability, and longer lifetime than macroscopic bubbles; thus, they provide an important impact in applications in the biomedical and chemical industries. However, a detailed understanding of the mechanism behind these mysteries of nanobubbles remains a challenge. Consistency between quantum computations and Raman spectrometric measurements confirmed our predictions that a nanobubble skin shares the same supersolidity with molecular clusters, skins of bulk water, and water droplets because of molecular undercoordination (fewer than four nearest molecular neighbors). Molecular undercoordination (coordination number Z cluster < Z surface < Z bubble < Z bulk = 4) shortens/extends the H-O/O:H bond and stiffens/softens its corresponding stretching phonons, whose frequency shift is proportional to the square root of the cohesive energy and inversely proportional to the segmental length. The strongly polarized O:H-O bond slows the molecular dynamics and increases the viscosity. The freezing temperature is lowered by the softened O:H bond, and the melting temperature is enhanced by the stiffened H-O bond. Therefore, the supersolid skin makes the nanobubbles thermally more stable, less dense, and stiffer and slows the dynamics of their molecular motion. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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