Tip convolution

More difficult is the differentiation of tip convolution effects if there is no hidden symmetry. In the images shown in Fig. 2.46, the tip was altered in the course of an experiment. In fact, the images show the same area of a vertically stretched... 

Fig. 3.38 Contact mode AFM height image of egg PC vesicles adsorbed on glass captured with an imaging force of 30 pN left) and 50 pN right). The halo in the fast scan direction right to left) indicates that the tip can no longer track the surface features accurately, when imaging force and noise of the deflection signal become comparable ( 30 pN in this case). When the imaging forces are increased to 50 pN, the surface is tracked better. The asymmetry of the features can be explained by tip convolution effects (asymmetry of the probe tip) [87]...

Fig. 3.62 Statistical analysis of the tapping mode AFM phase image (5x5 gm2) for PMMA - PB 80 - 20 blend after 24 h of ambient conditioning [134] shown as inset. The distribution of pixel values can be deconvoluted into three components (the corresponding curves have been superimposed on the histogram), thus reflecting the presence of the two distinct phases and a contribution that may originate from possible from tip convolution (or an intermediate phase) at the phase boundaries...

In semicrystalline polymers, fillers may act as reinforcement, as well as nucle-ation agents. For example in PP, nanoscale silica fillers may nucleate the crystallization resulting in spherulites that show enrichment in particles in the center of the spherulite (Fig. 3.64). For a quantitative analysis of, e.g., filler sizes and filler size distributions, high resolution imaging is necessary and tip convolution effects [137-140] must be corrected for. The particles shown below are likely aggregates of filler particles considering the mean filler size of 7 nm [136]. 

Tip broadening arises when the radius of curvature of the tip is comparable with, or greater than, the size of the feature trying to be imaged. Figure 3.13 illustrates this problem as the tip scans over the specimen, the sides of the tip make contact with the feature. This is what we call tip convolution. 

---