Rohrbeck Pascal N, Cavar Lukas D, Weber Franjo, Reichel Peter G, Niebling Mara, Weber Stefan A L
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
Department of Chemistry, University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
Beilstein J Nanotechnol. 2025 May 8;16:637-651. doi: 10.3762/bjnano.16.49. eCollection 2025.
We present multifrequency heterodyne electrostatic force microscopy (MFH-EFM) as a novel electrostatic force microscopy method for nanoscale capacitance characterization at arbitrary frequencies above the second cantilever resonance. Besides a high spatial resolution, the key advantage of the multifrequency approach of MFH-EFM is that it measures the second-order capacitance gradient at almost arbitrary frequencies, enabling the measurement of the local dielectric function over a wide range of frequencies. We demonstrate the reliable operation of MFH-EFM using standard atomic force microscopy equipment plus an external lock-in amplifier up to a frequency of 5 MHz, which can in principle be extended to gigahertz frequencies and beyond. Our results show a significant reduction of signal background from long-range electrostatic interactions, resulting in highly localized measurements. Combined with refined tip-sample capacitance models, MFH-EFM will enhance the precision of quantitative studies on dielectric effects in nanoscale systems across materials science, biology, and nanotechnology, complementing established methods in the field.
我们提出了多频外差式静电力显微镜（MFH-EFM），这是一种用于在高于悬臂梁二次共振的任意频率下进行纳米级电容表征的新型静电力显微镜方法。除了具有高空间分辨率外，MFH-EFM多频方法的关键优势在于它能在几乎任意频率下测量二阶电容梯度，从而能够在很宽的频率范围内测量局部介电函数。我们使用标准原子力显微镜设备加上一个外部锁相放大器，演示了MFH-EFM在高达5 MHz频率下的可靠运行，原则上该频率还可扩展到吉赫兹及更高频率。我们的结果表明，长程静电相互作用产生的信号背景显著降低，从而实现了高度局部化的测量。结合改进的针尖-样品电容模型，MFH-EFM将提高跨材料科学、生物学和纳米技术的纳米级系统中介电效应定量研究的精度，对该领域已有的方法起到补充作用。
