Direct Picosecond Determination of the Character of Vibrational Line Broadening in Liquids

1984 ◽  
pp. 274-277
Author(s):  
G. M. Gale ◽  
P. Guyot-Sionnest ◽  
W. Q. Zheng
Keyword(s):  
Line Broadening

The Use of the Pseudo-Voigt Function in the Variance Method of X-ray Line-Broadening Analysis

1997 ◽  
Vol 30 (4) ◽  
pp. 427-430 ◽  
Author(s):  
F. Sánchez-Bajo ◽  
F. L. Cumbrera
Keyword(s):  
Crystallite Size ◽  
Original Form ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Variance Method ◽  
The Mean ◽  
Voigt Function

A modified application of the variance method, using the pseudo-Voigt function as a good approximation to the X-ray diffraction profiles, is proposed in order to obtain microstructural quantities such as the mean crystallite size and root-mean-square (r.m.s.) strain. Whereas the variance method in its original form is applicable only to well separated reflections, this technique can be employed in the cases where there is line-profile overlap. Determination of the mean crystallite size and r.m.s. strain for several crystallographic directions in a nanocrystalline cubic sample of 9-YSZ (yttria-stabilized zirconia) has been performed by means of this procedure.

Evaluation Methods of Line Profiles

2014 ◽  
pp. 171-211
Keyword(s):  
Fourier Transforms ◽  
Qualitative Assessment ◽  
Peak Width ◽  
Line Profiles ◽  
Line Broadening ◽  
Evaluation Procedures ◽  
Fitting Procedures ◽  
Microstructure Model ◽  
Diffraction Peaks

The evaluation procedures of X-ray line profiles are overviewed in this chapter. These methods can be classified into four groups, namely (1) the most simple methods that evaluate only the breadths of diffraction peaks, (2) procedures using the Fourier-transforms of line profiles for the determination of the parameters of microstructures, (3) variance methods evaluating the restricted moments of peaks, and (4) procedures fitting the whole diffraction pattern. The crystallite size distribution and the densities of lattice defects cannot be determined from the peak width alone as the rule of summation of breadths of size, strain, and instrumental profiles depends on their shape. However, the breadth methods can be used for a qualitative assessment of the main origins of line broadening (size, dislocations, planar faults) (e.g. for checking the model of microstructure used in whole powder pattern fitting procedures). The application of Fourier and variance methods is limited if the diffraction peaks are overlapping. In the case of pattern fitting procedures, usually a microstructure model is needed for the calculation of the theoretical fitting functions. The reliability of these methods increases with increasing the number of fitted peaks.

An X-ray study of the crystal-structure of antigorite (With Plate V)

1945 ◽  
Vol 27 (188) ◽  
pp. 65-74 ◽  
Author(s):  
Endel Aruja
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
Line Broadening ◽  
X Ray ◽  
Complete Determination

Antigorite is a lamellar variety of serpentine, and is supposed to be a dimorphous form of chrysotile, which is finely fibrous. Its chemical composition is approximately H4Mg3Si2O9, which is taken as the basis of calculations here.This study was undertaken primarily because it was hoped that knowledge of the structure of antigorite would throw some light on that of chrysotile. Certain similarities between the two structures have been established, namely in the c(7·3kX or 14·6kX), and b(9·2kX) directions. There are two main differences, however. Firstly, imperfections which cause line broadening in the X-ray pattern of chrysotile, are absent in antigorite (apart from certain ‘streaks’). Secondly, the a(43·4kX) axis of antigorite is approximately eight times longer than the corresponding axis in chrysotile. A complete determination of the structure has not been achieved, but the X-ray pattern has been described, and some suggestions made as to the explanation of the peculiarities observed. A further study of the outstanding questions is in progress.

Structure Refinements in Chemistry and Physics. A Comparative Study Using the Rietveld and the Two- Step Method

1989 ◽  
Vol 33 ◽  
pp. 261-268 ◽  
Author(s):  
G. Will ◽  
E. Jansen ◽  
W. Schäfer
Keyword(s):  
Powder Diffraction ◽  
Structure Refinement ◽  
Powder Diffraction Data ◽  
Line Broadening ◽  
Step Method ◽  
Actual Structure ◽  
Structural Calculation ◽  
On Line ◽  
The Individual

Two strategies are at present commonly used in studying and refining crystal structures from powder diffraction data: the total pattern refinement proposed by Rietveid (1969) and the two-step method originally proposed and applied by Will (Will et al., 1965). The latter one works by separating-the intensity determination of the individual peaks from the actual structure refinement, structure analysis or any structural calculation (tor example based on line broadening). Both methods have their merits, and their drawbacks.

Determination of Strain Distributions in Aluminum Thin Films as a Function of Temperature by the use of Synchrotron Grazing Incidence X-Ray Scattering

1991 ◽  
Vol 239 ◽  
Author(s):  
Ramnath Venkatraman ◽  
Paul R. Besser ◽  
Sean Brennan ◽  
John C. Bravman
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Grazing Incidence ◽  
Surface Relaxation ◽  
Line Broadening ◽  
X Ray ◽  
Relaxation Effects ◽  
X Ray Scattering ◽  
Ray Scattering

ABSTRACTWe have measured elastic strain distributions with depth as a function of temperature in Al thin films of various thicknesses on oxidized silicon using synchrotron grazing incidence X-ray scattering (GIXS). Disregarding minor surface relaxation effects that depend on the film thickness, it is shown that there are no gross strain gradients in these films in the range of temperatures (between room temperature and 400°C) considered. We also observe X-ray line broadening effects, suggesting an accumulation of dislocations on cooling the films, and their annealing out as the films are reheated.

Determination of Total Absorption of Na3S → nP Transitions for 5 ≦ n ≦ 28

1978 ◽  
Vol 33 (4) ◽  
pp. 432-438
Author(s):  
L. Dressler ◽  
W. Behmenburg ◽  
J. Uhlenbusch
Keyword(s):  
Heat Pipe ◽  
Quantum Number ◽  
Total Absorption ◽  
Line Broadening ◽  
Absorption Tube ◽  
Number Range ◽  
Single Beam ◽  
Three Body ◽  
Absorption Measurements

Total absorption measurements of Na3S → nP transitions up to a main quantum number n = 28 have been performed at Na number densities in the range ≈ 1016 - 1017 cm-3 and temperatures ≈ 700-800 K. A heat pipe oven has been applied as an absorption tube in a single beam optical arrangement; experiment and data acquisition have been controlled by a computer. The results are compared with calculations using special assumptions with respect to line broadening mechanisms. The effect of binary and three-body collisions on total absorption is studied in detail. Within the pressure and main quantum number range investigated here a transition between the two types of interaction was demonstrated.

scholarly journals The Determination of Spectral Line Shapes for Hydrogenic Ions in Dense Plasmas

1977 ◽  
Vol 43 ◽  
pp. 3-3
Author(s):  
R. W. Lee
Keyword(s):  
Spectral Line ◽  
Ion Dynamics ◽  
Line Broadening ◽  
Dense Plasmas ◽  
Preliminary Results ◽  
Line Shapes ◽  
Hydrogenic Ions ◽  
Consistent Formulation ◽  
Fusion Type

The task of calculating line-shapes in ultra-dense fusion type plasmas is discussed. The application of line-broadening theory to derive a consistent formulation for ionized emitters including ion dynamics, Debye shifts and perturber-ion correlations is outlined. The difficulties in extending the standard theories are explored with special emphasis given to the modifications necessary to treat the cases which occur in the experimental situations. Preliminary results will be presented.

Monte Carlo determination of crystallite size of porous silicon from x-ray line broadening

2005 ◽  
Vol 87 (21) ◽  
pp. 211906 ◽  
Author(s):  
R. J. Martín-Palma ◽  
L. Pascual ◽  
P. Herrero ◽  
J. M. Martínez-Duart
Keyword(s):  
Monte Carlo ◽  
Porous Silicon ◽  
Crystallite Size ◽  
Line Broadening ◽  
X Ray
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