A robust off-resonance intermittent contact mode scanning force microscopy technique suitable for operation under different environmental conditions is presented. The technique relies on a multi-channel lock-in amplifier to measure multiple high harmonic magnitudes and phases. For distance control, the fundamental harmonic magnitude is used. With this, high intermittent contact frequencies become feasible even with older atomic force microscope data acquisition systems with limited measurement bandwidths, provided high frequency tip-sample distance actuation techniques are used. Suitable higher harmonic magnitude images provide a qualitative materials' contrast. If a sufficiently high number of high harmonic magnitudes and phases are recorded, force-distance curves at all imaged points can be reconstructed. From fitting models of the contact mechanics to force versus tip-sample penetration data, the elastic modulus of the sample can be obtained.

中文翻译：

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非共振间歇接触模式多谐波扫描力显微镜

提出了一种适用于不同环境条件下操作的稳健的非共振间歇接触模式扫描力显微镜技术。该技术依赖于多通道锁定放大器来测量多个高次谐波幅度和相位。对于距离控制，使用基波幅值。有了这个，即使使用具有有限测量带宽的旧原子力显微镜数据采集系统，只要使用高频尖端样品距离驱动技术，高间歇接触频率也变得可行。合适的高次谐波幅值图像提供了定性材料的对比度。如果记录了足够多的高次谐波幅度和相位，则可以重建所有成像点的力-距离曲线。