Topography mode

Fig. 8.8 Optical images (at an active zone I) of isolated silver clusters electrodeposited onto ITO by means of the double-pulse method ( i = —1,550 mV 2 = —VOO mV, 25 s) [37] (a) Scanning confocal microscopy image (topography mode), (b) Raman/fluorescence image of the same sample area, (c) SEM image corresponding to (a) and (b)...

The dc-mode or topography mode with quasi-static probe contact [5] is the most used, in which the AFM tip is in intimate repulsive contact with a smface, as shown in Figure 9.2. The contact mode is typically used for scanning hard samples and when a resolution of greater than 20 nm is required. The cantilevers are usually silicon (Si) or sUicon nitride (SiaN4), with typical resonant frequencies of 50 kHz and force constants below 1 N m . ... 

Fig. 21.7 AFM images (topography mode, 2.1 x 2.1 pm ) of cellulose from tunicin spread onto a freshly cleaved mica surface. Reproduced with permission from Elazzouzi-Hafraoui et al. (2008). Copyright 2008, American Chemical Society...

Figure 8. Crack opening displacement (COD) measured with an AFM in the topography mode. The figures display the width of the COD measured a few hours after the indent was made. The measurement was repeated after two days leading to a slight increase in the stress intensity factor. The data shown in Fig. 8a were obtained on the sample shown in Fig. 7a, and Fig. 8b corresponds to Fig. 7b.

To minimize effects of friction and other lateral forces in the topography measurements in contact-modes AFMs and to measure topography of the soft surface, AFMs can be operated in so-called tapping mode [53,54]. It is also referred to as intermittent-contact or the more general term Dynamic Force Mode" (DFM). A stiff cantilever is oscillated closer to the sample than in the noncontact mode. Part of the oscillation extends into the repulsive regime, so the tip intermittently touches or taps" the surface. Very stiff cantilevers are typically used, as tips can get stuck" in the water contamination layer. The advantage of tapping the surface is improved lateral resolution on soft samples. Lateral forces... 

In scanning electrochemical microscopy (SECM) a microelectrode probe (tip) is used to examine solid-liquid and liquid-liquid interfaces. SECM can provide information about the chemical nature, reactivity, and topography of phase boundaries. The earlier SECM experiments employed microdisk metal electrodes as amperometric probes [29]. This limited the applicability of the SECM to studies of processes involving electroactive (i.e., either oxidizable or reducible) species. One can apply SECM to studies of processes involving electroinactive species by using potentiometric tips [36]. However, potentio-metric tips are suitable only for collection mode measurements, whereas the amperometric feedback mode has been used for most quantitative SECM applications. 

Figure 2 shows the SEM image of the flake at a magnification of 350 x, as it was mounted on the conductive carbon tape. If there is a polymeric film covering the sample, the SEM will only show the surface topography of the film, not the structure residing below the polymeric film. EDS was conducted on two areas on the sample as indicated in Figure 2. The EDS analysis was conducted in square spot mode, approximately 1 pm by 1 pm in size. The elemental results are shown in Table 2. Based on these data sets it is apparent that the Type A defect is an iron-rich particle. Based on the lack of chromium or nickel the Type A defect is a particle of steel, not stainless steel.

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