Atomic force microscopy sample roughness

The formal potential is determined from the mean of the anodic and cathodic peak potential of the CV in Fig. 51.3. The titanium nitride samples are very smooth. Atomic force microscopy yielded a value of the roughness mean square of 0.516 nm on an area of 5 x 5 pm2. This means that the sample roughness is negligible against the radius of the UME and the working distance in the SECM experiment and the approximation of the sample surface as a simple plane is valid. 

So far, few authors [7,8] have reported X-ray reflectivity data for nitrides. This technique offers a very precise method of measuring the thickness of layers thinner than about 2000 A and their roughness. With a growing number of nitride samples of a very small roughness, reflectivity will soon become a commonly used characterisation technique. However, one should be aware that the level of surface roughness obtained from reflectivity often does not coincide with the data of atomic force microscopy (AFM) or even optical microscopy. This is because each technique has a different length scale and studies using complementary methods are necessary to obtain a real model of the surface. 

Atomic force microscopy has been up to now only scarcely used by the plasma processing community. Results mainly concern low-resolution measurements, that is modification of the surface roughness induced by the plasma [43,44], Micro masking effects have been observed when processing Si with a SF6 plasma beam at low temperature (Fig. 11) and correlated to the multi-layer adsorption of plasma species as observed by XPS [45], Further development of vacuum techniques should allow high resolution surface probe microscopy measurements on plasma-treated samples, and possibly lead to complementary information on adsorption kinetics, surface density of states. 

The materials analyzed were blends of polystyrene (PS) and poly(vinyl methyl ether) (PVME) in various ratios. The two components are miscible in all proportions at ambient temperature. The photooxidation mechanisms of the homo-polymers PS and PVME have been studied previously [4,7,8]. PVME has been shown to be much more sensitive to oxidation than PS and the rate of photooxidation of PVME was found to be approximately 10 times higher than that of PS. The photoproducts formed were identified by spectroscopy combined with chemical and physical treatments. The rate of oxidation of each component in the blend has been compared with the oxidation rate of the homopolymers studied separately. Because photooxidative aging induces modifications of the surface aspect of the material, the spectroscopic analysis of the photochemical behavior of the blend has been completed by an analysis of the surface of the samples by atomic force microscopy (AFM). A tentative correlation between the evolution of the roughness measured by AFM and the chemical changes occurring in the PVME-PS samples throughout irradiation is presented. 

Figures 33.13 shows the topography of the two plasma polymer layers deposited under different conditions on a polished iron surface. Both films show a similar topography as observed by atomic force microscopy, but the film deposited on O2 plasma-pretreated polished iron showed a little more grainy surface than (Ar + H2) plasma-pretreated sample. In Figure 33.14 the root mean square value is plotted against the film thickness. The grainy surface (O2 plasma pretreated), which showed a higher deposition rate, increased the roughness as the thickness increased as expected.

Other techniques, such as atomic force microscopy (AFM), and dynamic contact angle measurement (DCA) have been performed to measure the surface roughness and hydro-philicity of the sample, respectively. 

Figure 7.37. Spreading of ethylene glycol on three coated paper grades (art, silk and matt) with the same surface chemical composition. Each curve represents three different measurements at three different positions on the papers, and is perfectly reproducible. The rms roughness values of the samples depends on the scale length and the waveband analysed, but for all scales measured by atomic force microscopy and white-light profilometry increase in the order art < silk < matt (see also Figures 7.44 and 7.45 below)...

Figure 4.4 Surface roughness characterization using atomic force microscopy of the recycled silicone rubber samples (a) two-dimensional image of microstructure, scanning in transverse section, section penetration level of 5 pm (b) three-dimensional image of microstructure, scanning in transverse section, section penetration level of 5 pm (c) two-dimensional image of microstructure, scanning in hansverse section, penetration level section of 25 pm and (d) three-dimensional image of microstructure, scanning in transverse section, section penehation level of 25 pm.

Figure 8.2 Three-dimensional atomic force microscopy images of the surface of (a) uncoated, (b) single-layered, (c) double-layered, and (d) triple-layered coated samples, (e) roughness values of the deposited Hlms. ...

In high-resolution atomic force microscopy (AFM), a cantilever with a sharp tip is used to scan the sample surface. Deflection is measured using a laser beam reflected to a photodetector to generate a surface map of the specimen. Analysis of T. fusca cutinase-treated PET fibers by AFM has indicated an increase in surface roughness of the fibers [31],... 

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