qPlus型非接触原子力显微技术进展及前沿应用

刘梦溪,李世超,查泽奇,裘晓辉

Research Progress and Applications of qPlus Noncontact Atomic Force Microscopy

Meng-Xi LIU,Shi-Chao LI,Ze-Qi ZHA,Xiao-Hui QIU

图9 表面电荷分布测量

Fig 9 Measurements of the surface charge distribution (A) schematic of the measurement principle. At each tip position, the Δf is recorded as a function of the sample bias voltage (inset, red circles). The maximum of the fitted parabola (inset, solid black line) yields V* and Δf* for that position. The images were recorded with a copper-terminated tip on a 64 × 64 lateral grid at constant height; (B) local contact potential difference (LCPD) images of naphthalocyanine on NaCl (2 ML)/Cu (111); (C) DFT-calculated asymmetry of the z-component of the electric field above a free naphthalocyanine molecule at a distance d=0.5 nm from the molecular plane66. (D) 3D constant-height NC-AFM image of three Au adatoms on a NaCl (10 ML)/Cu (111) film with charge states neutral, positively. charged, and negatively charged. Height profiles are shown in the inset figure (solid line: Au-, dashed line: Au0, dotted line: Au+). (E) charge-state readout by recording Δf(V) spectra (dots) and determining the LCPD (triangles) from fitted parabolas (dashed lines)67. (F) model of tetrathiafulvalene-pyrazine2 (TTF-PYZ2) with the donor part in red and the acceptor part in blue; (G) constant-height NC-AFM image of TTF-PYZ2 in the"down"conformation with a CO tip. (H) LCPD (V*) maps of TTF-PYZ2 in the"down"conformation with a CO tip68; color online