| 摘要 |
A probe-sample separation dependence curve for frequency shift and energy dissipation at a certain point on a sample (3) is measured, while controlling frequency shift to be constant, using FM-AFM. A surface charge density conversion processing unit (241) finds and stores a formula for converting energy dissipation to charge density by performing fitting taking advantage of the fact that the curve can be approximated to an exponential function in a region where Pauli repulsion dominates. When the energy dissipation at each point on the sample (3) and the surface shape of the sample (3) are found by controlling the frequency shift to be constant, the surface charge density conversion processing unit (241) finds the surface charge density by using the conversion formula, a surface charge density imaging unit (253) creates an image for surface charge density distribution and displays the same, along with a surface topographic image and a dissipation image, on the screen of a display unit (29). Measurement time can be significantly reduced because conventional three-dimensional force mapping is unnecessary. Thus, the charge density distribution of a sample surface placed in a liquid can be obtained precisely and quickly. |
