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Wyszukujesz frazę "Shrivastava, B." wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
A Comparative Study of the Methods of Speciation Using X-ray Absorption Fine Structure
Autorzy:
Gaur, A.
Shrivastava, B.
Powiązania:
https://bibliotekanauki.pl/articles/1489872.pdf
Data publikacji:
2012-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Dm
Opis:
Determination of the chemical forms along with the relative quantity of the different species in a given sample, termed as speciation, can be done by analyzing X-ray absorption fine structure spectra. The different methods that can be used for speciation are: principal component analysis, target transformation, methods based on derivative spectra, method based on the relative position of the absorption edge, residual phase analysis, normalized difference absorption edge spectra analysis and linear combination fitting. An attempt has been made to make a comparative study of these different methods of speciation by recording the X-ray absorption fine structure at the copper K-edge in a mixture having cuprous oxide and cupric oxide in a specific ratio. The X-ray absorption fine structure spectra of the two oxides have also been recorded separately and the different characteristic X-ray absorption near edge structure features have been identified and their origins have been discussed. Speciation of the mixture has been done using these different methods and the results obtained have been compared and discussed.
Źródło:
Acta Physica Polonica A; 2012, 121, 3; 647-652
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
L$\text{}_{1}$ Absorption Edge of the 4f Heavy Rare-Earth Metals
Autorzy:
Shrivastava, B. D.
Joshi, S. K.
Powiązania:
https://bibliotekanauki.pl/articles/1920520.pdf
Data publikacji:
1992-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Dm
Opis:
The wavelengths of the L$\text{}_{1}$ absorption edges of the 4f heavy rare-earth metals ($\text{}^{65}$Tb to $\text{}^{71}$Lu) have been measured using a 40 cm curved crystal spectrograph of the Cauchois-type in the transmission mode. The measured values have been found to fit nicely in the modified Moseley diagrams. The absence of the white lines at the L$\text{}_{1}$ edges of the rare earths in metallic form and its occurrence in their compounds has been discussed.
Źródło:
Acta Physica Polonica A; 1992, 81, 3; 385-392
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fraction of Positronium Formation at Semiconductor Surface
Autorzy:
Shrivastava, S. B.
Upadhyay, A.
Powiązania:
https://bibliotekanauki.pl/articles/2010960.pdf
Data publikacji:
1999-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
71.60.+z
68.35.Fx
Opis:
The fraction of positronium formation (f$\text{}_{ps}$) has been calculated in Ge(110), Ge(111), Si(110) and Si(111) surfaces by solving the diffusion equation for positrons in semiconductors and by setting up the rate equation to describe the processes that are supposed to occur when a thermalised positron encounters the surface including the trapping of positrons in neutral and negative vacancies. Certain parameters used in the evaluation of f$\text{}_{ps}$, e.g., the bulk annihilation rate (λ$\text{}_{s}$), the positron diffusion length (L$\text{}_{+}$), the diffusion coefficient (D$\text{}_{+}$) and the implantation profile parameter (A), have been taken from the experiments. The calculated values of f$\text{}_{ps}$ as a function of incident positron energy and temperature in Ge(110) and Si(111) have been compared with the experimental results. It has been found that in general the calculated results are in good agreement with the experimental ones. The calculation also confirms that the trapping rate of positrons into negative vacancy has a T$\text{}^{-1}\text{}^{/}\text{}^{2}$ dependence with respect to the temperature.
Źródło:
Acta Physica Polonica A; 1999, 95, 6; 1005-1012
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positronium Fraction and Positron Life Time at Ni(110) and Ge(110) Surfaces
Autorzy:
Shrivastava, S. B.
Gupta, V. K.
Powiązania:
https://bibliotekanauki.pl/articles/1887749.pdf
Data publikacji:
1991-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.35.-p
25.30.Hm
Opis:
The fraction of positronium formation and the positron lifetime at Ni(110) and Ge(110) surfaces, when low-energy positrons incident on them, have been calculated using the rate equations approach and positron trapping in image potential well. The calculated results are compared with the available experimental results. The positronium fraction is overestimated at high temperatures in case of Ni(110).
Źródło:
Acta Physica Polonica A; 1991, 79, 6; 853-859
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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