Re-evaluation of the widely applied force-frequency relation for frequency-modulation AFM under solution
Re-evaluation of the widely applied force-frequency relation for frequency-modulation AFM under solution
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重新评估广泛应用的调频 AFM 力-频率关系的解
DOI：
10.1007/s12204-014-1549-8
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发表时间：
2014-10
影响因子：
--
通讯作者：
Czajkowsky Daniel M
中科院分区：
文献类型：
--
作者：
He Jian feng;Hu Jun;Sun Jie lin;Czajkowsky Daniel M
调频原子力显微镜（FM-AFM）是一种高度通用的表面科学工具。除了对表面进行成像外，FM-AFM还能够以高灵敏度测量AFM探针与表面之间的相互作用，从而提供亚纳米分辨率的化学信息。这是通过将实验中直接测量的频移去卷积为探针和样品之间的力来实现的。目前，广泛使用的方法来执行这种反褶积已被证明是准确的高品质（高Q）因子真空条件下。然而，在低品质（低Q）因素的条件下，例如在溶液中，尚不清楚该方法是否有效。以前的研究显然验证了这种关系的实验中的解决方案，通过比较这个方程计算的力与在单独的实验中获得的表面力装置（SFA）。在这里，我们表明，在解决方案中，一个更直接的比较，通过这种关系与直接测量的AFM悬臂梁偏转计算的力揭示了显着的差异，定性和定量。然而，我们也发现，有一些复杂的因素阻碍了这种比较。也就是说，虽然在直接测量（包括SFA数据）中与表面的接触是清楚的，但在FM-AFM情况下不太确定。因此，尚不清楚这两种方法是否测量相同的尖端-样品距离区域。因此，我们的研究结果表明，这种关系需要更彻底的验证，因为这种配方在溶液中的实验应用可能是无效的。
Frequency-modulation atomic force microscopy (FM-AFM) is a highly versatile tool for surface science. Besides imaging surfaces, FM-AFM is capable of measuring interactions between the AFM probe and the surface with high sensitivity, which can provide chemical information at sub-nanometer resolution. This is achieved by deconvoluting the frequency shift, which is directly measured in experiments, into the force between the probe and sample. At present, the widely used method to perform this deconvolution has been shown to be accurate under high quality (high-Q) factor vacuum conditions. However, under low quality (low-Q) factor conditions, such as in solution, it is not clear if this method is valid. A previous study apparently verified this relation for experiments in solution by comparing the force calculated by this equation with that obtained in separate experiments using the surface force apparatus (SFA). Here we show that, in solution, a more direct comparison of the force calculated by this relation with that directly measured by the cantilever deflection in AFM reveals significant differences, both qualitative and quantitative. However, we also find that there are complications that hinder this comparison. Namely, while contact with the surface is clear in the direct measurements (including the SFA data), it is less certain in the FM-AFM case. Hence, it is not clear if the two methods are measuring the same tip-sample distance regimes. Thus, our results suggest that a more thorough verification of this relation is required, as application of this formulation for experiments in solution may not be valid.
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影响因子：
56.9
作者：
Lantz, MA;Hug, HJ;Güntherodt, HJ
通讯作者：
Güntherodt, HJ
影响因子：
17.1
作者：
Daniel S. Wastl;F. Speck;Elisabeth Wutscher;M. Ostler;T. Seyller;F. Giessibl
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Daniel S. Wastl;F. Speck;Elisabeth Wutscher;M. Ostler;T. Seyller;F. Giessibl
影响因子：
3.7
作者：
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通讯作者：
O'Shea, S. J.
影响因子：
56.9
作者：
Welker, Joachim;Giessibl, Franz J.
通讯作者：
Giessibl, Franz J.
影响因子：
3.5
作者：
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通讯作者：
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