AI 中文总结
该研究针对CR-AFM传统激发易掩盖共振的问题，提出iDART技术，结合布朗运动激发与主动电激发，实现高速接触共振追踪，为常规AFM扫描速率下的共振增强纳米力学成像提供实用方案。
AI 中文摘要
接触共振原子力显微镜（CR-AFM）可提供接触刚度、耗散和机电响应的纳米级图谱，但传统压电声学激发会因致动器和样品架模式掩盖悬臂梁共振。纯布朗运动激发可避免这种传递函数背景，但其小振幅通常需要平均处理，无法适配常规成像。我们引入干涉式双交流共振追踪（iDART），将正交相位差干涉测量与双频共振追踪相结合。通过将干涉光斑定位在第一接触共振模式的位移最大值附近，探测器噪声基底降至悬臂梁非共振热位移以下。布朗光谱识别接触模式并定义追踪频率，而主动电激发提供像素分辨成像所需的信噪比。同步低频与共振测量显示，电驱动和光热驱动均可提升振幅和相位通道的对比度，且不会显著改变接触共振。这些结果为常规AFM扫描速率下的共振增强、无驱动纳米力学成像提供了实用途径。
英文摘要
Contact-resonance atomic force microscopy (CR-AFM) provides nanoscale maps of contact stiffness, dissipation, and electromechanical response, but conventional piezoacoustic excitation can obscure the cantilever resonance with actuator and sample-holder modes. Pure Brownian excitation avoids this transfer-function background, yet its small amplitude generally requires averaging that is incompatible with routine imaging. We introduce interferometric dual-AC resonance tracking (iDART), which combines quadrature-phase differential interferometry with two-frequency resonance tracking. By positioning the interferometric spot near the displacement maximum of the first contact-resonance mode, the detector noise floor is reduced below the off-resonance thermal displacement of the cantilever. Brownian spectra identify the contact mode and define the tracking frequencies, while active electrical excitation provides the signal-to-noise ratio required for pixel-resolved imaging. Simultaneous low-frequency and resonant measurements show that both electrical and photothermal drive increases contrast in the amplitude and phase channels without appreciably shifting the contact resonance. These results establish a practical route to resonance-enhanced, drive free nanomechanical imaging at conventional AFM scan rates.
Comments13 pages, 4 figures
