A method of comparison between a force curve measured on a solvated surface and the solvation structure

TL;DR

This paper discusses a theoretical method to compare AFM-measured force curves with the actual solvation structure, clarifying their relationship using statistical mechanics to improve understanding of AFM data.

Contribution

It introduces a new theoretical approach to relate measured mean forces from AFM to the true solvation structure, which was previously not well understood.

Findings

Established a theoretical relation between mean force and solvation structure.

Proposed a method to compare experimental force curves with simulated or measured solvation structures.

Enhanced understanding of AFM force measurements in solvated surfaces.

Abstract

Recent atomic force microscopy (AFM) can measure force curves between a probe and a sample surface in solvent. The force curve is thought as the solvation structure in some cases, because its shape is generally oscilltive and pitch of the oscillation is about the same as diameter of the solvent. However, it is not the solvation structure. It is just only a mean force between the probe and the sample surface. A theoretical relation between the mean force and the solvation structure is not clearly known. Therefore, the relation must be elucidated theoretically to deepen understanding of the mean force measured by the AFM. In this letter, we briefly explain the relation and a method for comparing the measured mean force and the solvation structure (that obtained by a simulation, a liquid theory, or a x-ray reflectivity) by using basic statistical mechanics of liquid.