Fast and accurate expression for the Voigt function. Application to the determination of uranium M linewidths

2008 ◽  
Vol 63 (9) ◽  
pp. 962-967 ◽  
Author(s):  
Silvina P. Limandri ◽  
Rita D. Bonetto ◽  
Héctor O. Di Rocco ◽  
Jorge C. Trincavelli
Keyword(s):  
Accurate Expression ◽  
Voigt Function

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.

Determination of the Coherency Strain of γ and γ′ Phases in Nickel-Base Superalloys at High Temperatures

1992 ◽  
Vol 36 ◽  
pp. 515-526
Author(s):  
Katsumi Ohno ◽  
Tadaharu Yokokawa ◽  
Toshihiro Yamagata ◽  
Hiroshi Harada ◽  
Michio Yamazaki ◽  
...  
Keyword(s):  
Lattice Misfit ◽  
Profile Fitting ◽  
Overlapping Peaks ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
L12 Structure ◽  
Fcc Structure ◽  
Type Nickel ◽  
Voigt Function

AbstractA method for using syncrotoron-radiation parallel-beam X-ray diffractometry for precise lattice parameters and strains of γ-γ′ type Nickel base superalloys at elevated temperature is described. The superalloys have γ′ precipitates which are an ordered L12 structure based on Ni3Al, in y-matrices having a disordered FCC structure. Lattice misfit between γ and γ′ phases was very small and peaks reflected from γ and γ′ phases made unresolved clusters of peaks.Profile fitting with a pseudo-Voigt function is used to resolve overlapping peaks. Instrumental broadening of the peak profile was removed using a deconvolution method. The standard errors of the calculated peak angle were less than 0.002°. The elastic strain of the γ′ precipitates in the alloys were smaller than those of γ-matrices.

Lattice Parameter Determination Using Synchrotron Powder Data

1986 ◽  
Vol 30 ◽  
pp. 373-382 ◽  
Author(s):  
W. Parrish ◽  
M. Hart ◽  
T. C Huang ◽  
M. Bellotto
Keyword(s):  
Lattice Parameter ◽  
Parameter Determination ◽  
Wavelength Selection ◽  
Profile Fitting ◽  
Angle Correction ◽  
Average Accuracy ◽  
The Mean ◽  
The Individual ◽  
Voigt Function

AbstractA method for using synchrotron-radiation parallel-beam X-ray diffractometry for precision measurement of scattering angles and lattice parameters is described. The important advantages of the method are the high P/B made possible by wavelength selection and high source intensity, the symmetrical profiles and the absence of most systematic errors making it unnecessary to use standards. Profile fitting with a pseudo-Voigt function is used to determine 2θ to 0.0001º. The zero-angle correction and lattice parameter were determined from least-squares refinement and the average accuracy of observed-calculated 2θs was 0.0020°. Average values of ∆d/d = ∆a/a directly calculated from the individual hkl measurements ranged from 2x 10-5 to 5.7 x 10-5. The precision estimated from the standard deviation of the mean is in the 10-6 range and 1 ppm precision was obtained for Si. The determination of the exact wavelength selected remains to be solved, but ratios of lattice spacings to standards such as NBS SRM 640a can be determined.

Determination of nonlinear optical properties using the Voigt function: Stochastic considerations

2010 ◽  
Vol 111 (1) ◽  
pp. 155-159 ◽  
Author(s):  
A. Mendoza-García ◽  
J.L. Paz ◽  
A. Romero-Depablos ◽  
E. Castro ◽  
P. Martín
Keyword(s):  
Optical Properties ◽  
Nonlinear Optical ◽  
Nonlinear Optical Properties ◽  
Voigt Function

More Accurate Formulas for Determination of Absolute Atom Concentration Using Electron Energy-Loss Spectroscopy

2016 ◽  
Vol 22 (6) ◽  
pp. 1381-1388
Author(s):  
Noureddine Hadji
Keyword(s):  
Free Electron ◽  
Dispersion Coefficient ◽  
Approximate Expression ◽  
Universal Function ◽  
Atom Concentration ◽  
Upper Limits ◽  
Accurate Expression ◽  
Electron Energy Loss ◽  
Physical Quantities

AbstractWhen the value of the dispersion coefficient is “greatly different from 0.5,” as is the case for “free-electron” materials such as sodium (Na), the approximate expression for the volume plasmon critical wave vector (PCV) used by Hadji stops being valid and a different, more precise, expression must be used. Here a more accurate PCV formula is used to get a more accurate expression for plasmon scattering cross-section per atom (PSCA) species. This PSCA is then employed to calculate some physical quantities for several “free-electron” materials and together with the techniques from the quoted paper to determine values for physical quantities from amorphous silicon (a-Si) experimental data. The program source used to obtain these values is supplied. Any valid formula for the PSCA species is, in fact, relevant for use together with the two quoted techniques. The PCV and the dispersion coefficient have upper limits. Negative dispersion coefficient values are allowed. A PCV-related dimensionless universal function that can represent all ideal “free-electron” materials is given. “Not greatly different from 0.5” is mathematically expressed.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

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