Surface charge density measuring apparatus using an atomic force microscope

摘要

Using frequency-shift constant control, FM-AFM is used to measure the probe-sample distance dependency curve of frequency shift and energy dissipation at a certain point on sample (3). In the range where the Pauli repulsive force is dominant, the surface charge density conversion processing unit (241) converts from energy dissipation to charge density by performing fitting utilizing the fact that the above curve can approximate an exponential function, And store it. When the energy dissipation of each point on the sample (3) together with the surface shape on the sample (3) is determined by constant frequency shift control, the surface charge density conversion processing unit (241) calculates the surface charge density by using the conversion formula The surface charge density image forming unit (253) creates a surface charge density distribution image and displays it on the screen of the display unit (29) together with the surface irregularity image and the dissipated image. Since three-dimensional force mapping is unnecessary unlike the conventional method, the measurement time can be greatly shortened. In this way, it is possible to quickly and accurately acquire the charge density distribution image of the sample surface placed in the liquid.