981 resultados para Stark, Efecte de
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The determination of the Stark broadening parameters of Sn ions is useful for astrophysicists interested in the determination of the density of electrons in stellar atmospheres. In this paper, we report on the calculated values of the Stark broadening parameters for 171 lines of Sn iii arising from 4d105sns (n= 6–9), 4d105snp (n= 5, 6), 4d105p2, 4d105snd (n= 5–7), 4d105s4f and 4d105s5g. Stark linewidths and line shifts are presented for an electron density of 1023 m−3 and temperatures T= 11 000–75 000 K. These have been calculated using a semi-empirical approach, with a set of wavefunctions obtained from Hartree–Fock relativistic calculations, including core polarization effects. The results obtained have been compared with available experimental data. These can be used to consider the influence of Stark broadening effects in A-type stellar atmospheres
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In this paper, we report calculated values of the Stark widths and shifts for 72 spectral lines of Pb v. They were calculated using the Griem semi-empirical approach. A set of wavefunctions obtained from Hartree–Fock relativistic calculations including core polarization effects was used. Stark widths and shifts corresponding to lines arising from 5d9ns (n = 7, 8), 5d9 6p, 5d9 6d and 5d9 5f configurations of Pb v. Stark widths and shifts are presented for an electron density of 1017 cm−3 and temperatures T = 1.6–5.0 (104 K). The 2142.5, 2167.9 and 2278.6 Å lines of Pb v recently measured are included in our calculations. In this case, we have included for comparison calculations without core polarization effects. There is good agreement between our calculations and the above-cited experimental values.
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We have determined matrix elements for all experimental configurations of Ca III, including the 3s3p63d configuration. These values have been obtained using intermediate coupling (IC). For these IC calculations, we have used the standard method of least-squares fitting from the experimental energy levels, using the computer code developed by Robert Cowan. In this paper, using these matrix elements, we report the calculated values of the Ca III Stark widths and shifts for 148 spectral lines, of 56 Ca III spectral line transition probabilities and of eight radiative lifetimes of Ca III levels. The Stark widths and shifts, calculated using the Griem semi-empirical approach, correspond to the spectral lines of Ca III and are presented for an electron density of 1017 cm?3 and temperatures T = 1.0?10.0 (×104 K). The theoretical trends of the Stark broadening parameter versus the temperature are presented for transitions that are of astrophysical interest. There is good agreement between our calculations, for transition probabilities and radiative lifetimes, and the experimental values presented in the literature. We have not been able to find any values for the Stark parameters in the references.
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In the present work we report theoretical Stark widths and shifts calculated using the Griem semi-empirical approach, corresponding to 237 spectral lines of MgIII. Data are presented for an electron density of 1017 cm?3 and temperatures T = 0.5?10.0 (104 K). The matrix elements used in these calculations have been determined from 23 configurations of MgIII: 2s22p6, 2s22p53p, 2s22p54p, 2s22p54f and 2s22p55f for even parity and 2s22p5ns (n = 3?6), 2s22p5nd (n = 3?9), 2s22p55g and 2s2p6np (n = 3?8) for odd parity. For the intermediate coupling (IC) calculations, we use the standard method of least-squares fitting from experimental energy levels by means of the Cowan computer code. Also, in order to test the matrix elements used in our calculations, we present calculated values of 70 transition probabilities of MgIII spectral lines and 14 calculated values of radiative lifetimes of MgIII levels. There is good agreement between our calculations and experimental radiative lifetimes. Spectral lines of MgIII are relevant in astrophysics and also play an important role in the spectral analysis of laboratory plasma. Theoretical trends of the Stark broadening parameter versus the temperature for relevant lines are presented. No values of Stark parameters can be found in the bibliography.
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Yvonne Wilson is a woman of achievement, accomplishment, and ambition. It all started when she enrolled in Lincoln University; the only public institution for higher education in Missouri that admitted African Americans. She later went on to become a teacher, principal and systems director in the Kansas City School District. Mrs. Wilson was involved in many civic/social activities including the Metropolitan Community Colleges and the Bruce Watkins Cultural Heritage Center. She had many accomplishments including her positions as the President of Lincoln University Board of Curators and the first African American President of the Missouri Association of Elementary School Principals. Finally, one of her top accomplishments was being appointed to the Missouri House of Representatives.
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After weeks of debate Taylor’s proposal, House Bill No. 195 was passed and signed by Governor Lloyd Stark.
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La realització pràctica d’experiments és fonamental en qualsevol disciplina científica. Per això, en aquest treball exposem una sèrie d’experiències de física senzilles i sorprenents que ens permetran reforçar diversos conceptes físics d’una manera amena, utilitzant materials molt assequibles i barats. Amb la realització d’aquests experiments volem estimular la curiositat de l’alumnat i el plaer per la investigació i el descobriment de nous fenòmens físics. Aquestes experiències estan adreçades tant a estudiants d’educació secundària i batxillerat com a alumnes dels primers cursos d’universitat. Hem dissenyat i dut a terme experiències de diversos camps de la física, entre els quals hi ha algunes pràctiques per a posar de manifest la conservació del moment lineal, o l’efecte Coandă en fluids en moviment, i també experiments de física atòmica relacionats amb l’emissió atòmica en l’espectre visible, que posen de manifest la quantització de l’energia dels nivells atòmics. Amb aquestes experiències volem motivar els alumnes en l’estudi i l’interès per la física des d’una perspectiva diferent de l’habitual.
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One leaf containing a page of handwritten biographical notes on Revolutionary War hero General John Stark in Bentley's hand. The note is written on the verso of a short letter from J. Pitcairn regarding a deliver for the "Rev. D. Bently" dated March 2, 1810. The notes were likely copied from the biographical sketch published in the Essex Register May 1, 1810.
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Mode of access: Internet.
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"Civil War Centennial issue. Facsimile copy ... from the original in the Western History Department, Denver Public Library."
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Mode of access: Internet.
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At head of title: NBS Project 8440-11-84141.
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Mode of access: Internet.