Borgani Riccardo, Haviland David B
Nanostructure Physics, KTH Royal Institute of Technology, 10691 Stockholm, Sweden.
Rev Sci Instrum. 2019 Jan;90(1):013705. doi: 10.1063/1.5060727.
We present an alternative approach to pump-probe spectroscopy for measuring fast charge dynamics with an atomic force microscope (AFM). Our approach is based on coherent multifrequency lock-in measurement of the intermodulation between a mechanical drive and an optical or electrical excitation. In response to the excitation, the charge dynamics of the sample is reconstructed by fitting a theoretical model to the measured frequency spectrum of the electrostatic force near resonance of the AFM cantilever. We discuss the time resolution, which in theory is limited only by the measurement time, but in practice is of order 1 ns for standard cantilevers and imaging speeds. We verify the method with simulations and demonstrate it with a control experiment, achieving a time resolution of 30 ns in ambient conditions, limited by thermal noise.
我们提出了一种利用原子力显微镜（AFM）测量快速电荷动力学的泵浦-探测光谱学替代方法。我们的方法基于对机械驱动与光或电激发之间互调的相干多频锁相测量。响应于激发，通过将理论模型拟合到AFM悬臂共振附近静电力的测量频谱来重建样品的电荷动力学。我们讨论了时间分辨率，理论上它仅受测量时间限制，但实际上对于标准悬臂和成像速度而言约为1纳秒。我们通过模拟验证了该方法，并通过对照实验进行了演示，在环境条件下实现了30纳秒的时间分辨率，受热噪声限制。
