Constant current mode STM

Figure 26. Constant current mode STM image of isolated (A), self-organized in close-packed hexagonal network (C) and in fee structure (E) of silver nanoclusters deposited on Au(l 11) substrate (scan size (A) 17.1 x 17.1 nm, f/t=—IV, /t=ltiA, (C) 136 X 136 nm, f/t = — 2.5 V, /t = 0.8 tiA, (E) 143 x 143 nm, = —2.2 V, /, = 0.72 nA). I U) curves and their derivatives in the inserts of isolated (B), self-organized in close-packed hexagonal network (D) and in fee structure (F) of silver nanoclusters deposited on Au(l 11) substrate. (Reprinted with permission from Ref. [58], 2000, Wiley-VCH.)...

Figure 5.67 Left column Constant-current mode STM image of isolated (a), self-organized in close-packed hexagonal network (c), and fee structure (e) of silver nanopartides deposited on an Au(lll) substrate. Scan sizes ...

Fig. 4. Operational modes for stm. (a) Constant height mode, (b) Constant current mode (18).

Figure 2.26 The expected trajectory that would be followed by an STM tip in constant current mode over a metal sample. The surface has one alien atom more electronegative than its neighbours. From Christensen (1992).

Eigure 6.18(top) displays a submolecular-resolution STM image of the afc-plane of an in-air cleaved TTE-TCNQ single crystal obtained in a constant current mode in... 

Fig. 26a. Scanning tunneling microscopic image of a 310nmx310nm area of bare Au film epitaxially grown on a mica substrate (Au mica) measured in air constant current mode bias (Vb) of + 50 mV, tunneling current (I,) of 10 nA. b STM image of a 3.5 nm x 3.5 nm area of a bare Au/mica film constant current mode Vb = 4- 4.9 mV I, = 3.0 nA [219]...

Fig. 27a-d. STM image of a 100 nm x 100 nm a n-oetadecanethiol film coated on Au/mica b same area after 10 s of etching mode (Vb = 10 mV, I, = 10 nA) over a 10 nm x 10 nm area (within area shown by broken line% c same area after 10 min of continuous normal scanning d after 35 min normal scanning. All images were taken in constant current mode, Vb = + 1V, and I, = 1 nA [219]... 

Fig. 1. Schematic illustration of the constant current mode of STM operation.

Fig. 3. A series of STM images (40 nmx 40 nm) incompletely reacted H/Si(lll) surfaces upon irradiation (447nm) in a solution of 1-decene for 3 (top left), 15 (top right), 30 (bottom left) and 120 (bottom right) minutes. Images were acquired in constant current mode at 20pA and sample biases of-2.7 to -3.8 V. Reprinted from [21].

Figure 6. Low-resolution STM survey image of a partly oxidized graphite flake. The asymmetric V-shape of the deep trenches is a tip artefact. Conditions Burleigh AR1S 6000, air, W tip, constant current mode, gap voltage 200 mV.

Figure 16. STM images (Burleigh ARIS 6000. air, W tip. constant current mode, 200 mV gap voltage, graphite natural single crystals, oxidation in air at 900 K) of (a) pristine and (b) oxidized graphite surfaces.

The image can be quite different, depending on the user-selected constant "set-point" bias (within a range of about 2 V) between tip and substrate the bias will move the tip up and down relative to the substrate. There are two ways of collecting an STM image (a) the constant-current mode, where the tip... 

The high resolution TEM study was carried out with a JEOL 200 CX microscope equipped with high resolution polar pieces. The STM used for the study of HOPG graphite was of the same type as that described by Hansma and Tersoff (5). Imaging was performed in air, in the constant current mode. Further details were given previousiy (6). 

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