Sample scanning tunnelling

Rohrer G 1993 The preparation of tip and sample surfaces for STM experiments Scanning Tunnelling Microscopy and Spectroscopy ed D A Bonnell (Weinheim VCH) ch 6... 

Scanning tunnel microscopy (STM) was chosen as a tool for realization of this task (Wilkins et al. 1989). CdS nanoparticles were formed in a bilayer of cadmium arachidate deposited onto the surface of freshly cleaved graphite (Erokhin et al. 1995a). The graphite was used as the first electrode. Initially, STM was used for locahzing the position of the particles. Eigure 28 shows the images of different areas of the sample. The particles are vis-... 

Landman, U., and W. D. Luedtke, Consequences of tip-sample interactions, in Scanning Tunneling Microscopy III, R. Wiesendanger and H. J. Guntherodt Eds., Springer-Verlag, Berlin, 1993. Lorentz, W. J., and W. Plieth, Eds., Electrochemical Nanotechnology, Wiley-VCH, New York, 1996. 

Gopakumar TG, Meiss J, Pouladsaz D, Hietschold M (2008) HOMO-LUMO gap shrinking reveals tip-induced polarization of molecules in ultrathin layers tip-sample distance-depen-dent scanning tunneling spectroscopy on d8 (Ni, Pd, and Pt) phthalocyanines. J Phys Chem C 112 2529-2537... 

The scanning tunneling microscope uses an atomically sharp probe tip to map contours of the local density of electronic states on the surface. This is accomplished by monitoring quantum transmission of electrons between the tip and substrate while piezoelectric devices raster the tip relative to the substrate, as shown schematically in Fig. 1 [38]. The remarkable vertical resolution of the device arises from the exponential dependence of the electron tunneling process on the tip-substrate separation, d. In the simplest approximation, the tunneling current, 1, can be simply written in terms of the local density of states (LDOS), ps(z,E), at the Fermi level (E = Ep) of the sample, where V is the bias voltage between the tip and substrate... 

Fig. 19 AFM images of G-wires freshly adsorbed onto mica imaged via tapping mode (a). Same sample imaged by the same tip 24 h later after drying in an oven at 37 °C (b). Low current scanning tunneling microscopy image of G-wires freshly adsorbed on mica (c). Note the preferential orientation is not a sample preparation artefact, e.g., due to rinsing [126]. Reprinted with permission...

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