Line profile Voigt

In these and in many other reports, the size analysis is based on a full profile fit determined by using predefined line profiles (Voigt, pseudo-Voigt) and an intensity fitting according to the Rietveldt method (McCusker et al., 1999). This procedure, which requires substantial effort in data analysis, is reliable, provided that no changes in sample geometry... 

It is essential to correctly evaluate the absorption cross-section a relative to the laser line profile, the spectral resolution of the light collection optics, and the natural HO line width as influenced by Doppler, Voigt, or collisional broadening. The principles governing absorption measurements of HO over a distance through the atmosphere are discussed by Hiibler et al. (38). 

Blickensderfer et al. (119) have recently extended the Samson theory to include various vessel geometries under conditions of pure Doppler, pure Lorentz, and Voigt (a combination of Doppler, Lorentz, and natural broadening) line profiles. The quenching cross section can be obtained also by a dynamic method in which the decay of the fluorescence intensity is measured after the exciting light is cut off. If the initial fluorescence intensity is / and the intensity after a lime f is If, we obtain... 

Gaussian Laser Profile-Voigt Atom Profile. This case turns out to be a better approximation of our experimental situation, i.e., the laser FWHM is fairly broad compared to the absorption line width and the absorption profile of atoms in an atmospheric combustion flame is described by a Voigt profile. Here the laser is assumed to have a Gaussian spectral profile as well as a Gaussian atomic absorption profile. In this case, convolution of two Gaussian functions is still a Gaussian function. Evaluation of the ratio n2/nT, and the fluorescence radiance. Bp, allows determination of the half width of the fluorescence excitation profile, 6X... 

The line shapes are described by Voigt functions, which reflect the Lorentzian line profiles due to natural line width and Gaussian profiles due to Doppler broadening. The instrumental broadening by the rocking curve of the crystal, de-focusing and the finite resolution of the detector is described well by a Voigt profile shape too [3[. 

Terms included in Equation (26) are the IP, which can be expressed by the FT of a pseudo-Voigt function (Tp ) obtained from a suitable line profile standard (Section 13.2.3), contributions from size ( / ), dislocations ( / )> faulting (Ahk + anti-phase domain boundaries (Aff f). Expressions for various... 

A parametric description of the IP can be obtained by modelling the pattern of a line profile standard with pseudo-Voigt functions (see Chapters 4 and 5 and Section 13.2.3 in this chapter) ... 

Figure J. 23. Lorentzian, Doppler, and Voigt spectral line profiles for approximately equal half widths and intensities. (From Andrews et al.., 1987).

Armstrong, B.H., Spectrum line profiles The Voigt function. J Quant Spectrosc Radiat Transfer 7, 61, 1967. 

Calculation of mean crystallite size, lattice strain and frequency distributions of crystallite sizes from the same XRD line-profiles used for crystallinity determinations. In addition to the application of the Scherrer equation, two single-line methods were used the variance method of Wilson (1963) (Akai and To th 1983 Nieto and Smchez-Navas 1994), and the Voigt method of Langford (1978) in combination with single-line Fourier analysis (Akai et al. 1996, 1997, 2000 Warr 1996 Jiang et al. 1997 Li et al. 

Figure 1. Relations between illite ciystallinity (IC) and mean ciystallite size (a) and lattice strain (b) as calculated from XRD line-profiles by the modified Voigt method. Data from Akai et al. (1 996, 2000), Jiang et al. (1997)andLietal. (1998).

Figure 2.3 Comparison of Gauss (blue line) and Lorentz (green line) curves of equal area and same FWHM, and a Voigt (red line) profile produced by convoluting the other two curves...

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