Kattel Subash, Scougale William R, Murphy Joseph R, Pasco Samuel R, Ackerman John, Alvarado Vladimir, Rice William D
Department of Physics and Astronomy, University of Wyoming 1000 E. University Ave., Laramie, WY, 82071, USA.
Department of Chemical Engineering, University of Wyoming 1000 E. University Ave., Laramie, WY, 82071, USA.
Small. 2020 Oct;16(42):e2003892. doi: 10.1002/smll.202003892. Epub 2020 Sep 28.
Reliably determining the physical properties of ice (e.g., crystal structure, adhesion strength, interfacial state, and molecular orientation) has proven to be both challenging and highly dependent on experiment-specific conditions, including surface roughness, ice formation, water purity, and measurement method. Here, non-destructive measurements of single-layer graphene (SLG) interfaced with bulk ice are used to determine temperature-dependent, ice-induced strain and estimate ice-created strain elastic density in SLG. The use of SLG enables the precise study of interfacial strain by monitoring the 2D Raman mode. Upon ice formation, a clear, ≈2 cm decrease in the 2D mode frequency is observed, which is ascribed to a 0.012% biaxial tensile shear strain at the ice-SLG interface. From this shear strain value, the ice-created SLG elastic strain energy density is estimated to be 2.4 μJ m . In addition to these Raman strain measurements, intentionally ionized water is used to show that water-mediated charging of the SLG surface manifests itself in a distinctly different manner than ice-induced strain. Finally, the localized nature of the Raman probe is used to map SLG regions with and without ice, suggesting that this method cannot only determine ice-induced interfacial strain, but also correlate ice adhesion properties with surface roughness and topology.
事实证明，可靠地确定冰的物理性质（例如晶体结构、粘附强度、界面状态和分子取向）既具有挑战性，又高度依赖于特定实验条件，包括表面粗糙度、冰的形成、水的纯度和测量方法。在这里，利用与块状冰接触的单层石墨烯（SLG）的非破坏性测量来确定与温度相关的、冰诱导的应变，并估计SLG中冰产生的应变弹性密度。通过监测二维拉曼模式，SLG的使用使得能够精确研究界面应变。在冰形成时，观察到二维模式频率明显下降约2 cm，这归因于冰 - SLG界面处0.012%的双轴拉伸剪切应变。根据该剪切应变值，估计冰产生的SLG弹性应变能密度为2.4 μJ/m²。除了这些拉曼应变测量外，还使用了经过有意电离的水来表明，SLG表面的水介导充电与冰诱导应变的表现方式明显不同。最后，利用拉曼探针的局部特性绘制有冰和无冰的SLG区域，这表明该方法不仅可以确定冰诱导的界面应变，还可以将冰的粘附特性与表面粗糙度和拓扑结构相关联。
