Profile fitting

Overall, up to five parameters per diffraction peak can be refined 20, /, 

and p (or r ). In order to proceed with profile fitting using non-linear least squares refinement, all parameters should be assigned reasonable initial values. This is usually achieved in the following way  

Depending on the quality of the pattern, profile fitting can be conducted in several different ways. They differ in how peak positions and peak shape parameters are handled, assuming that integrated intensities are always refined independently for each peak, and a single set of parameters describes a background within the processed range  

All possible variables (positions and shapes) are refined independently for each peak or with some constraints. For example, an asymmetry parameter is usually a variable, common for all peaks full width at half maximum or even all peak shape function parameters may be common for all peaks, especially if a relatively narrow range of Bragg angles is processed. When justified by the quality of data, an independent fit of all or most parameters produces best results. A major problem in this approach (i.e. all parameters are free and unconstrained) occurs when clusters of reflections include both strong and weak Bragg peaks. Then, peak shape parameters corresponding to weak Bragg peaks may become 

The under peaks change sign several times, and they are 

---

The usual experimental situation is that of a sessile drop and, as with the pendant drop, it is necessary to determine a shape parameter and some absolute length. Thus /3 may be determined by profile fitting, and Ze measured, where Ze is the distance from the plane at = 90 to the apex. If the drop rests with... 

Figure 4-164 shows a steel body core bit with a long-taper, stepped profile fitted with impregnated natural diamond blocks as the primary cutting elements. The bit has no inner cone. Since there is no specific code for the natural diamond/steel body combination, the letter O (other) is used as the cutter type/ body material code. The profile code 3 is used to describe the long outer taper with little or no inner cone depth. The hydraulic design code 5 indicates a fixed... 

An alternative approach, giving better results if the peak width is very close to the instrumental one, is to take into account the instrumental contribution (by a convolution of the refined peak due to the sample and the instrumental profile) during the profile fitting procedure [42]. 

This profile fits perfectely the SERM concept. By designing molecules that exert specific effects on different organs and fine-tuning those molecules to a given woman s advantage, we would be able to influence health and survival expectancies. 

In principle, one can take the interpretation further and calculate what oxygen concentration profile fits the measurements of the O/Ag ratio best. In fact, Baschenko et al. [39] did this and concluded that the subsurface oxygen resides mainly in the third and fourth atomic layer below the surface. Although the result appears plausible, it should be noted that such calculations are only permitted when the surface satisfies the requirements of lateral homogeneity and absence of roughness discussed above. As the O/Ag experiments were done with polycrystalline foils, one might wonder whether too detailed an analysis is warranted. Anyhow, the work forms a nice illustration of what angle-dependent XPS can achieve on catalytically relevant adsorbate systems. 

The use of parallel beam optics as a means for determining the polymorphic composition in powder compacts has been discussed [45]. In this study, compressed mixtures of known polymorphic composition were analyzed in transmission mode, and the data were processed using profile-fitting software. The advantage of using transmission, rather than the reflectance, is that the results were not sensitive to the... 

W. M. Reichert, J. T. Suci, J. T. Ives, and J. D. Andrade, Evanescent detection of adsorbed protein concentration-distance profiles Fit of simple models to variable-angle total internal reflection fluorescence data, Appl. Spectrosc. 41, 503-507 (1987). 

When all the phases present were identified, we can quantify their volume fraction in the analyzed volume similarly to the way the Rietveld-method is used for phase analysis in XRD. A whole profile fitting is used in ProcessDifraction, modeling background and peak-shapes, and fitting the shape parameters, thermal parameters and volume fractions. Since the kinematic approximation is used for calculating the electron diffraction intensities, the grain size of both phases should be below 10 nm (as a rule of... 

Rossmann, M. G. (1979). Processing oscillation diffraction data from very large unit cells with an automatic convolution technique and profile fitting. /. Appl. Cryst. 12, 225-238. 

Preparing the Intensity Data for Structure Solution Profile Fitting. 140... 

After the unit cell has been determined, the next stage is to prepare the intensity data for space group determination and structure solution using an appropriate profile fitting technique such as the Pawley method [30] or the Le Bail method [31]. The aim of this stage of the structure determination process is to fit the complete experimental powder XRD profile by refinement of variables that describe ... 

The resulting reaction profile fits the scheme shown in Eq. (4) (wherein C = cucurbituril, Z = azide, Y = alkyne, T = triazole). The individual (binary) dissociation constants for the reactants plus cucurbituril were independently... 

Figure 3. Rotational broadening of He I X4471, assuming angular momentum conservation. The best profile fit is obtained with Vrot sin i = 450 km/s.

The obtained "fit point" parameters are now used for the calculation of "final models 1, and the resulting synthetic spectra are compared with the observation as a final check. We restrict the representation (Fig. 1) to the model C, since the corresponding profile fits for the other two mass-loss rates would appear very similar. 

Figure 12 shows a sample profile from the growth of gallium-doped germanium by Wang (6). The profile fits equation 21, with an equilibrium segregation coefficient k of 0.087 and keS of 0.09-0.11... 

---