Department of Applied Physics, Graduate School of Engineering, Osaka University, Suita, Osaka, Japan.
Ultramicroscopy. 2010 May;110(6):612-7. doi: 10.1016/j.ultramic.2010.02.020. Epub 2010 Feb 23.
Extension of AFM-based viscoelasticity measurement into a frequency-resolved analysis is attempted. A cantilever immersed into and interacting with distilled water was employed for the trial system. Using a home-built wideband magnetic excitation AFM, a step force with a transient time less than 1micros is applied to the AFM cantilever and its deflection is measured. The 1st and 2nd mode resonance ringing of the cantilever was suppressed using quality-factor-control technique, so that the measurement system becomes equivalent to driving a resonance-free virtual cantilever within the bandwidth limited by the surviving 3rd mode resonance. From the obtained response of the cantilever deflection, a frequency-dependent complex compliance of the cantilever-water system was derived in a frequency range of 1-100kHz. Effect of water confining between the tip and a mica substrate is discussed.
尝试将基于原子力显微镜的粘弹性测量扩展到频率分辨分析中。试验系统采用浸入并与蒸馏水相互作用的悬臂梁。使用自制的宽带磁激励原子力显微镜，向原子力显微镜悬臂施加具有小于 1 微秒瞬态时间的阶跃力，并测量其挠度。通过品质因数控制技术抑制悬臂的第 1 模态和第 2 模态谐振振铃，使得测量系统等效于在由第 3 模态谐振幸存的带宽内驱动无谐振的虚拟悬臂。从悬臂挠度的获得响应中，在 1-100kHz 的频率范围内推导出悬臂-水系统的频率相关复柔量。讨论了在尖端和云母基底之间的水限制的影响。
