Harmonic excitation imaging system for tapping-mode atomic force microscopy

Abstract

The invention discloses a harmonic excitation imaging system for a tapping-mode atomic force microscopy. The harmonic excitation imaging system comprises a function generator, a low-pass filter and a phase lock amplifier added to the prior tapping-mode atomic force microscopy, wherein the function generator is connected with the excitation signal input end of an AFM probe exciter; the phase lock amplifier is connected between a photoelectric four quadrant receiver and an AFM controller; and the low-pass filter is connected in series between the function generator and the phase lock amplifier. The harmonic excitation imaging system is imaging technology which adopts a harmonic superposed signal as an excitation source in a tapping mode and the phase lock amplifier to obtain the high-order harmonic components of probe motion and makes use of the amplitudes and phases of the high-order harmonic components to acquire more information and higher resolution.

Description

technical field [0001] The present invention relates to an imaging system, more particularly, to a harmonic excitation imaging system suitable for tapping mode atomic force microscope. Background technique [0002] Atomic Force Microscope (AFM) is an instrument that uses the interaction force between atoms and molecules to observe the microscopic topography of the surface of objects. The atomic force microscope has a nanometer-scale probe fixed on a micron-scale elastic cantilever that can be sensitively manipulated. When the probe is very close to the sample, the force between the atoms at the top and the surface atoms of the sample will bend the cantilever and deviate from the original position. Location. By reconstructing the three-dimensional image according to the deviation or vibration frequency of the probe when scanning the sample, the morphology or composition information of the sample surface can be obtained indirectly. [0003] Traditional tapping mode AFM imagi...

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Problems solved by technology

[0004] However, a large number of studies have shown that the phase contrast image can only reflect the non-conservative force interaction between the probe and the sample, and cannot reflect the difference in the conservative force interaction between different regions of the sample.

In addition, the phase contrast image cannot reflect the composition difference of each region of the sample under the condition of small amplitude non-contact imaging

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