Temperature dependence of solvation forces as measured in atomic force microscopy
Temperature dependence of solvation forces as measured in atomic force microscopy
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DOI：
10.1063/1.3096967
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发表时间：
2009-04-07
影响因子：
4.4
通讯作者：
O'Shea, S. J.
中科院分区：
文献类型：
--
作者：
Lim, L. T. W.;Wee, A. T. S.;O'Shea, S. J.
原子力显微镜 (AFM) 用于研究温度对限制在 AFM 尖端和石墨表面之间的液体八甲基环四硅氧烷、正十六烷和正十二烷醇中溶剂化力的影响。在所有测量温度 (298-348K) 下，所有三种液体都可以观察到离散的溶剂化层。然而，随着温度升高，测得的溶剂化力的大小显着降低，并且可以观察到的溶剂化振荡的数量减少。溶剂力本身与温度的关系很弱，最合理的解释是我们正在测量层是如何从尖端样品间隙中挤压出来的。挤出过程是一种热激活现象，导致力振荡的幅度随温度发生巨大变化。基于转移率理论进行了简单的分析。溶剂化力随温度的巨大变化对于使用 AFM 测量局部力具有影响，特别是在解释生物相互作用和单个粗糙体摩擦方面。
An atomic force microscope (AFM) has been used to study the effect of temperature on solvation forces in the liquids octamethylcyclotetrasiloxane, n-hexadecane, and n-dodecanol confined between the AFM tip and a graphite surface. Discrete solvation layers can be observed for all three liquids at all the temperatures measured (298-348K). However, with increasing temperature there is a significant decrease in the magnitude of the measured solvation forces and a reduction in the number of solvation oscillations which can be observed. Solvation forces per se are only weakly temperature dependent and the most plausible explanation is that we are measuring how the layers are squeezed from the tip-sample gap. The squeeze out process is a thermally activated phenomenon and gives rise to the large change in the magnitude of the force oscillations with temperature. A simple analysis is provided based on transition rate theory. The large change in solvation force with temperature has implications for the measurement of localized forces using AFM, particularly in interpreting biological interactions and single asperity friction.