Color atomic force microscopy: A method to acquire three independent potential parameters to generate a color image

Abstract

Atomic force microscopy has enabled imaging at the sub-molecular level, and 3D mapping of the tip-surface potential field. However, fast identification of the surface still remains a challenging topic for the microscope to enjoy widespread use as a tool with chemical contrast. In this paper, as a step towards implementation of such function, we introduce a control scheme and mathematical treatment of the acquired data that enable retrieval of essential information characterizing this potential field, leading to fast acquisition of images with chemical contrast. The control scheme is based on the tip sample distance modulation at an angular frequency ω, and null-control of the ω component of the measured self-excitation frequency of the oscillator. It is demonstrated that this control is robust, and that effective Morse Parameters that give satisfactory curve fit to the measured frequency shift can be calculated at rates comparable to the scan. Atomic features with similar topography were distinguished by differences in these parameters. The decay length parameter was resolved with a resolution of 10 pm. The method was demonstrated on quenched silicon at a scan rate comparable to conventional imaging.

Bottom-tracking: the possibilities and physical meaning of keeping the bottom of the frequency shift in atomic force microscopy

“…Detailed mathematical discussions can be found in the literature and its supplementary material. 11) As a general tendency, the depth of the FC well becomes shallower with increasing A due to averaging, and the point of local minima moves away from the sample surface. There is no general analytical formula to express df min for a finite value of A, but in the case were A is negligibly small, it can be expressed as…”

“…2, the trace of Bottom-tracking shows less atomic corrugations than the constant-frequency control, which may result in an image with less contrast. However, the method has such positive aspects as: (i) the acquired trace is unique for a given amplitude of drive, (ii) tip-sample distance is maintained even in the presence of thermal drift compared to constant-height imaging, (iii) unlike the constant-frequency-shift mode, the working point can be set at the bottom of the FC, and (iv) position modulation around the bottom of the FC gives the 2ω component arising from the FC, which contains information on the width of the FC and the width of the potential well as demonstrated by Allain et al 11)…”

“…Position modulation techniques in the vertical or lateral directions can be found in the literature. [11][12][13][14][15][16][17] Although it is not hard to imagine that force at the atomic level may be the fingerprint of the atomic species and the characteristics of interatomic interactions, 18) it was not until 2001 that such expectations were experimentally confirmed with the AFM. 19,20) Force measurement evolved into 3D mapping of the force and potential landscape.…”

Basic concepts and physical-chemical phenomena, that have conceptual meaning for the formation of systemic clinical thinking and formalization of the knowledge of systemic structural-functional organization of the human’s organism

“…Группа японских ученых разработала методику, с помощью которой атомно-силовой микроскоп можно использовать для получения цветных изображений. Она делает возможным не только определение особенностей топографии поверхности объекта, но и измерение значения трёх параметров потенциала Морса, которые затем преобразуют в цветовой код, отражающий локальный его химический состав [143].…”