Film diffraction pattern

FIGURE 11.1 Electron diffraction patterns of the linear chain carbon films (a-c), the distribution of electron diffraction intensity, its atomic arrangement (g), the Langmuir-Blodgett multi-layered film diffraction patterns (d,e). 

Figure 15. Flat-film diffraction pattern of polypropylene fibers...

When a ledge is formed on an atomically smooth monolayer during tire formation of a thin film the intensity of the diffraction pattern is reduced due to the reduction in the beatrr intensity by inelastic scattering of electrons at the ledge-monolayer junction. The diffraction intensity catr thus be used during deposition of several monolayers to indicate the completion of a monolayer through the relative increase in intensity at tlris time. Observation of this effect of intensity oscillation is used in practice to count the number of monolayers which are laid down during a deposition process. 

Figure 18.5 Schematic view of a diffraction experiment, (a) A narrow beam of x-rays (red) is taken out from the x-ray source through a collimating device. When the primary beam hits the crystal, most of it passes straight through, but some is diffracted by the crystal. These diffracted beams, which leave the crystal in many different directions, are recorded on a detector, either a piece of x-ray film or an area detector, (b) A diffraction pattern from a crystal of the enzyme RuBisCo using monochromatic radiation (compare with Figure 18.2b, the pattern using polychromatic radiation). The crystal was rotated one degree while this pattern was recorded.

The examples in Figure 3 illustrate these possibilities. Figure 3a shows a diffraction pattern from a single crystal Fe thin film, oriented with the [001] crystal axis... 

Interdiffusion of bilayered thin films also can be measured with XRD. The diffraction pattern initially consists of two peaks from the pure layers and after annealing, the diffracted intensity between these peaks grows because of interdiffusion of the layers. An analysis of this intensity yields the concentration profile, which enables a calculation of diffusion coefficients, and diffusion coefficients cm /s are readily measured. With the use of multilayered specimens, extremely small diffusion coefficients (-10 cm /s) can be measured with XRD. Alternative methods of measuring concentration profiles and diffusion coefficients include depth profiling (which suffers from artifacts), RBS (which can not resolve adjacent elements in the periodic table), and radiotracer methods (which are difficult). For XRD (except for multilayered specimens), there must be a unique relationship between composition and the d-spacings in the initial films and any solid solutions or compounds that form this permits calculation of the compo-... 

Grain size in textured films. For films having a preferred growth direction—e.g., (111)—LEED can be used to determine the preferred direction and the grain size parallel to the surfrce. The preferred direction is obtained from the symmetry of the diffraction patterns, while the grain size is obtained from the shape in angle of diffracted beams. 

Surface-sensitive diffraction is, for the most part, restricted to analysis of surfaces of single crystals and overlayers and films on such surfaces. If a polycrystalline sample is illuminated using a beam of low-energy electrons, each crystallite surfiice exposed will create its own diffraction pattern, all of which will be superimposed on the fluorescent screen detector. If more than a few orientations are illuminated by the beam, the pattern becomes too complicated to analyze. Flowever, if the size of the... 

Films produced in oxalic acid contain smaller amounts (about 3%) of the electrolyte and only traces of chromium are found in chromic acid films. Sealed films show the electron diffraction pattern of the monohydrate, bohmite. 

For this compound, the diffraction pattern (see Fig. 16-34) indicates that the as-deposited film is considerably more crystalline than that of Ooct-OPV5-CN. Annealing carried out at 160°C for 5 min results in a polycrystalline film with im-... 

Figure 9-7. Elastic electron-diffraction pattern of a highly textured hcxaphenyl film. The Miller indices arc assigned using the intcrplauar spacings calculated in Kef. 11371. Inset Intensity of the f020) peak as a function of the angle between momentum transfer and the Teflon rubbing direction (see text) - taken from Ref. 138. ...

Some films containing deposited nickel together with copper were annealed at 500°C in order to ensure the homogenization of the alloys. After their cooling down to room temperature the X-ray diffraction patterns demonstrated phase segregation of the alloys similar to that described by Sachtler et al. (45). 

The diffraction pattern of the sample of chlorine hydrate consisted of powder lines on which were superimposed a large number of more intense single-crystal reflections for some planes only the latter were visible. The intensities of the lines were estimated by comparison with a previously calibrated powder photograph, and were averaged for several films pre-... 

A fiber-diffraction pattern is recorded on a flat-film camera in which the fiber-to-photographic film distance is typically in the range of 3 to 4 cm. During exposure to X-rays, the specimen chamber is continuously flushed with a slow and steady stream of helium gas that has been bubbled through a saturated salt solution so that (a) the fiber is maintained at a constant desired r.h. and (b) fogging of the photographic film from air scattering is reduced. 

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