研究目的
To propose a method that makes readily accessible an arbitrary number of exact higher harmonics by externally driving them with amplitudes above the noise level, enabling multiple contrast channels sensitive to compositional variations.
研究成果
The proposed method makes readily accessible an arbitrary number of exact higher harmonics by externally driving them with amplitudes above the noise level, enabling multiple contrast channels sensitive to compositional variations. Higher harmonic phase shifts also provide the means to decouple the true topography from that induced by compositional heterogeneity.
研究不足
The study acknowledges that technical issues might arise from the multiple excitation of exact frequencies and from the set-up required to detect variations in higher harmonic phase. The working amplitudes should lie in the range of 1 to 100 pm to provide enough phase contrast.
1：Experimental Design and Method Selection:
The study involves numerical integration of the equation of motion to show that the external introduction of exact harmonic frequencies does not compromise the fundamental frequency. Thermal fluctuations are considered within the detection bandwidth of interest.
2：Sample Selection and Data Sources:
The focus is on dynamic atomic force microscopy (AFM) with gentle interactions and minimal invasiveness.
3：List of Experimental Equipment and Materials:
Standard cantilevers for AM AFM with parameters k = 2 N/m, Q = 100, ω = 2π·70 kHz and R = 7 nm.
4：Experimental Procedures and Operational Workflow:
The methodology includes externally driving an arbitrary number of exact higher harmonics above the noise level and analyzing the phase shifts and amplitudes.
5：Data Analysis Methods:
The analysis involves monitoring variations in higher harmonic phase shifts and amplitudes in response to variations in the tip–sample force.
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