Surface Charge Affects the Structure of Interfacial Ice
Surface Charge Affects the Structure of Interfacial Ice
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DOI：
10.1021/acs.jpcc.5b08371
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发表时间：
2016-02-25
影响因子：
3.7
通讯作者：
Dhinojwala, Ali
中科院分区：
文献类型：
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作者：
Anim-Danso, Emmanuel;Zhang, Yu;Dhinojwala, Ali
我们对带电表面附近的水分子冻结进行了研究，以阐明水的取向对冰结构的影响。我们观察到，当水被冻结在带正电的蓝宝石表面附近时，冰的信号强度比液态水的信号强度要高，这是先前理论研究的预期。然而，当水冻结在带负电的蓝宝石表面(使用氢氧化钠作为pH调节器)时，信号强度会降低。当使用氢氧化铯(CsOH)和四甲基氢氧化铵(N(CH3)(4)OH)作为pH调节剂时，冰冻时的信号衰减相同。由于Na+、Cs+和N(CH3)(4)(+)离子具有不同的水化性质，因此排除了阳离子对冰信号强度衰减的特定影响。在云母表面(固有带负电)上的实验也显示，冰的信号强度衰减与带负电的蓝宝石表面相似。我们的结论是，表面附近的水分子的取向对冰的结构起着重要作用。这些结果对于理解冰核的强度和带电表面附近的冰附着强度具有重要的意义。
We have conducted studies on the freezing of water molecules next to charged surfaces to elucidate the effect of water orientation on the structure of ice using sum frequency generation spectroscopy. We observed that when water is frozen next to a positively charged sapphire surface, the signal intensity of ice is higher than that of liquid water as so expected from previous theoretical studies. However, when water is frozen next to a negatively charged sapphire surface (using NaOH as pH adjuster), the signal intensity decreases. The same signal attenuation upon freezing is obtained when cesium hydroxide (CsOH) and tetramethylammonium hydroxide (N(CH3)(4)OH) are used as pH adjusters. Since Na+, Cs+, and N(CH3)(4)(+) ions have different hydration properties, the cation specific effect for this attenuation in signal intensity for ice is ruled out. Experiments on a mica surface (inherently negatively charged) also showed similar attenuation in signal intensity for ice as negatively charged sapphire surface. We conclude that the orientation of the water molecules next to a surface plays an important role in the structure of ice. These results have important implications in understanding the strength of ice nucleation and strength of ice adhesion next to charged surfaces.