Cross Sections For Na Research Articles

Collisions between sodium atoms and nitrogen molecules: rotational excitation and fine-structure-changing collisions

The formalism describing low-energy collisions between a linear molecule and an atom with fine-structure levels is set forth. It is shown that the resulting equations are rendered more tractable by making either the fixed-nucleus or averaged-field approximations. These are usually complementary approximations, but it is shown by physical arguments and numerical calculation that they are in good agreement for Na-N2 collisions. Using the surfaces calculated in an earlier paper, rotational excitation and fine-structure-changing cross sections for Na(2S, 2P)-N2(j) collisions at energies between 0.004 and 0.05 eV are presented, the molecule being in its ground vibrational state. The results are in agreement with the single available measurement.

Measurements of Charge Transfer Cross Sections for Ne<SUP>+</SUP> and Ne<SUP>++</SUP> in He and Ne

Measurements of Charge Transfer Cross Sections for Ne<SUP>+</SUP> and Ne<SUP>++</SUP> in He and Ne

Study of the sputtering of adsorbates by low energy ions (O on Ni)

Sputtering or ion impact desorption of adsorbed layers has been studied by low energy ion scattering and model calculations. For adsorption of a monolayer or less (e.g. oxygen on nickel) the desorption by ions can be readily observed by He + ion scattering from the development of the adsorbate and substrate signal as a function of time. Desorption cross sections for Ne + and He + ions in the energy range from 500 eV to 1600 eV are given. These results are compared with the model calculations and the influence of various parameters can be studied by this comparison. The contribution of different processes to the sputtering mechanism is discussed.

Multiconfiguration Hartree-Fock calculation of photoionization cross sections of the rare gases

A multiconfiguration Hartree-Fock calculation is used to test the hypothesis that ground-state correlations involving excitation of a single of electrons from an outer $p$ shell into $d$ orbitals are the dominant ones in the photoionization cross sections of Ne, Ar, Kr, and Xe. Dramatic improvement in the agreement of dipole length and dipole velocity forms of the cross section is obtaining in going from a Hartree-Fock to a multiconfiguration Hartree-Fock calculation. Results are found to be comparable to recent values obtained using the random-phase approximation with exchange and the $R$ matrix.

Molecular Beam Studies of Total Cross Sections of Na Scattered by Different Gases

A molecular beam scattering apparatus has been set up for the study of total cross section of alkali and alkali halide molecules scattered by different gases. The resolution of the apparatus is fairly high so that accurate correction for finite resolution can be mode. The Ishii-Nakayama backstreaming effect of the McLeod gauge used for calibration purpose has been eliminated. The scattering cross sections for Na atom with Ar, O 2 , N 2 , He and H 2 have been measured. The results show the satisfactory performance of the apparatus. The cross sections obtained have been compared with the theoretical values.

Cross sections for the quenching of lead resonance radiation

Pb atoms were excited and studied by optical techniques using signal averaging and phase sensitive detection. Cross sections for the quenching of the $^{3}P_{1}^{o}$ excited state of Pb were measured by observing the reduction of the atomic fluorescence as a function of foreign gas pressure. The cross sections for the following quenchers measured at 900\ifmmode^\circ\else\textdegree\fi{}K were (in ${\mathrm{\AA{}}}^{2}$) for ${\mathrm{N}}_{2}$, 18; CO, 27; ${\mathrm{CO}}_{2}$, 63; and for ${\mathrm{CH}}_{4}$, 55 with an estimated uncertainty of \ifmmode\pm\else\textpm\fi{} 20%. Upper limits on the quenching cross sections of Ne, Ar, Kr, Xe, ${\mathrm{H}}_{2}$, and ${\mathrm{D}}_{2}$ were also measured.

Low-energy differential elastic scattering of Ne* (3P) by Kr(1S)

Differential elastic cross sections for Ne* (3P) scattered by Kr are obtained at three relative kinetic energies, 64 to 74 meV. Location and shape of rainbow maxima, observed at all energies, are used to determine the well depth and potential minimum for a double-Lennard-Jones potential. The results, ε=8.05±0.49 meV, and rm=4.91±0.64 Å are similar to those for Na+Kr and are substantially different from those of Ne+Kr. A value of 2.11 Å for the atomic radius of Ne* is obtained which is close to that previously reported for Na.

Ionization of sodium and potassium vapour by 20-100 keV H+and He+ions

A modulated crossed-beam technique has been used to study the ionization of potassium and sodium vapour by 20-100 keV H+ and He+ ions. Absolute cross sections sigma e for electron production have been determined from the gross yield of electrons. Mass spectrometric measurements of the relative abundance of secondary ion species, together with measurements (in a subsidiary experiment) of the total one-electron capture cross section sigma 10 have been used to determine cross sections for Na+, K+, and K2+ formation. Proton impact ionization cross sections are shown to be in generally poor accord with theoretical estimates based on both the classical impulse and Born approximations.

Charge-exchange cross sections forNe+andAr+incident on Cs

Charge-exchange cross sections for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Ne</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Ar</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>incident on Cs

Correction [to “He and Ne cross sections in natural Mg, Al, and Si targets and radionuclide cross sections in natural Si, Ca, Ti, and Fe targets bombarded with 14- to 45-MeV protons”

Correction [to “He and Ne cross sections in natural Mg, Al, and Si targets and radionuclide cross sections in natural Si, Ca, Ti, and Fe targets bombarded with 14- to 45-MeV protons”

He and Ne cross sections in natural Mg, Al, and Si targets and radionuclide cross sections in natural Si, Ca, Ti, and Fe targets bombarded with 14- to 45-Mev protons

In three sets of irradiations at Texas A&M's Variable Energy Cyclotron, stacks of thin Mg, Al, Si, Ca, Ti, and Fe foils were bombarded with 1016 to 1018 protons of energies 14 to 45 Mev to determine cross sections of He and Ne and of certain radionuclides. The 22Na activity in the Mg and Si target foils, the 48V activity in the Ti foils, the 57Co, 51Cr, and 52Mn activities in the Fe targets, and the 47Sc activity in the Ca targets were measured by gamma ray spectrometry. Cross sections were calculated by using the 22Na activity in the Mg foils as an internal monitor.

Energy dependence for Ne *(2p 53s 3P) + Ar ionization total cross sections

The ionization (Penning and associative) total cross sections for Ne *(2p 53s 3P) + Ar are calculated semiclassically in the energy range of 0.001 to 1000 eV and compared with recent experimental results of Micha et al.

Improved total inelastic scattering cross section for the rare gases

New calculations for the total inelastic electron scattering cross sections for the elements H, He, Ne, Ar and Kr at incident electron energies of 500 eV and 40 keV are presented. The calculations are given for both an old and a new formula for the total inelastic scattering cross section and are compared where possible with the results of more rigorous calculations. The new results predict that the total inelastic scattering cross sections will be lower for the heavier elements by a factor of 2–4 than previously reported. In addition the value of the cross section for Ne in the low energy region is found to be surprisingly small.

Deexcitation Probabilities of Ne(&lt;sup&gt;3&lt;/sup&gt;P&lt;sub&gt;2&lt;/sub&gt;) by Kr for the Case E &amp;lt;&amp;lt; D

The deexcitation probability calculation of the total Penning ionization cross section for Ne(3P2) by Kr has been made in the region of the collisional energy from 18.5 to 38.1 meV. Considering the magnitude of the mean collisional energy with respect to D, the application of the analysis in the case E &gt;&gt; D is expected to be more appropriate than in the case E &lt;&lt; D. Theoretical investigations of Ne(3P2) by Kr for the case E &gt;&gt; D are also needed.Keywords: metastable atoms, resonance atoms, deexcitation cross sections, pulse radiolysis, impact parameter.DOI: 10.3126/jncs.v24i0.2390Journal of Nepal Chemical Society Vol.24 Page 45-48

Deexcitation Probabilities of Ne(3P2) by Ar for the Case E &lt;&lt; D

The deexcitaion probability calculation of the total Penning ionization cross section for Ne(3P2) by Ar has been made in the region of the collisional energy from 18.5 to 38.1 meV. Comparing the magnitude of the mean collisional energy with respect to D, the application of the analysis in the case E &gt;&gt; D is expected to be more appropriate than in the case E &lt;&lt; D. More advance theoretical investigations for Ne(3P2) by Ar should consider the further understanding. Keywords: Deexcitation cross section; Collisional energy; Pulse radiolysis method; Metastable atoms; Impact parameter.DOI: 10.3126/jncs.v24i0.2382 Journal of Nepal Chemical Society, Vol. 24, 2009 Page: 19-23

Deexcitation Probabilities of Ne(&lt;sup&gt;3&lt;/sup&gt;P&lt;/sub&gt;2&lt;/sub&gt;) by Xe for the Case E &amp;lt;&amp;lt; D

The deexcitaion probability calculation of the total Penning ionization cross sectionfor Ne(3P2) by Xe has been made in the region of the collisional energy from 18.5 to 38.1meV. The experimental cross sections have been compared with the deexcitation probabilityfor Ne(3P2) by Xe. Considering the magnitude of the mean collisional energy with respect toD, the application of the analysis in the case E &gt;&gt; D is expected to be more appropriatethan in the case E &lt;&lt; D. For further insight into this results, it is also of great importanceto evaluate theoretical investigations of Ne(3P2) by Xe for the case E &gt;&gt; D.Keywords: Metastable atoms, deexcitation probabilities, pulse radiolysis, collisionalenergy, potential well depthDOI: 10.3126/jncs.v25i0.3304Journal of Nepal Chemical Society Volume 25, 2010 pp 70-74

A Study of Na-O2Collisions Using Merging Beams

A merging beams technique was used to study two-body collisions of Na and ${\mathrm{O}}_{2}$. In particular, some processes which resulted in positive ions, and negative ions or electrons were investigated. These processes were endothermic and included charge transfer, ionization, and rearrangement. Interaction energies $W$ were varied from threshold, i.e., several electron volts up to 25 eV. In the center-of-mass system and for processes resulting in ${\mathrm{Na}}^{+}$ formation, scattering of ${\mathrm{Na}}^{+}$ was predominantly at angles less than 90\ifmmode^\circ\else\textdegree\fi{} from the well-defined direction of the reactant Na. For the reaction Na+${\mathrm{O}}_{2}$\ensuremath{\rightarrow}${\mathrm{Na}}^{+}$+${\mathrm{O}}_{2}^{\ensuremath{-}}$, a very narrow lab energy distribution of ${\mathrm{Na}}^{+}$ was observed for which scattering of ${\mathrm{Na}}^{+}$ in the center-of-mass system was confined to just a few degrees about the Na direction. For this distribution it was also observed that at least 92% of the excess translational energy of the reactants (i.e., interaction energy minus the endothermicity) was converted into translational energy of the products. Therefore, 8% or less went into internal energy of the products. The cross section for Na + ${\mathrm{O}}_{2}$\ensuremath{\rightarrow}${\mathrm{Na}}^{+}$+${\mathrm{O}}_{2}^{\ensuremath{-}}$ leading to the formation of ${\mathrm{Na}}^{+}$ in this narrow energy distribution is called ${Q}_{a}$. At or near threshold (i.e., 4.71 eV), ${Q}_{a}$ rises from zero and reaches a maximum at about 8 eV. From absolute measurements, ${Q}_{a}\ensuremath{\approx}0.05$ ${\mathrm{\AA{}}}^{2}$ at $W=10$ eV. The existence of Na${\mathrm{O}}^{+}$, first reported by Rol and Entemann, was confirmed in the study of collisions of Na and ${\mathrm{O}}_{2}$ leading to rearrangement.

Vergleichsmessung totaler Alkali-Edelgas-Querschnitte

Total scattering cross sections of Na and Cs on Ar and Kr and of Rb on Kr have been measured relative to the corresponding K cross sections by a fast direct comparison technique. From the data ratios of van der Waals constants are derived, which show good agreement with recently published semiempirical values.

Double Electron Ejection Resulting from Photo-Ionization in the Outermost Shell of He, Ne, and Ar, and Its Relationship to Electron Correlation

The probability of ejecting two or more electrons by the interaction of an x ray with the outermost shell of He, Ne, and Ar has been investigated. The relative abundances of doubly charged to singly charged ions following x irradiation have been measured with a charge spectrometer. These ratios are essentially constant over the range of x-ray energies from 3 to 8 times the threshold for double ionization. They are, respectively, 0.035, 0.14, and 0.17 for He, Ne, and Ar. Energy spectra for electrons ejected in photo-ionization have been measured with an electron spectrometer. In addition to characteristic photolines, continuum spectra are found, which are related to double electron ejection. The probabilities for double electron ejection as determined from these spectra are in agreement with those obtained by charge spectrometry. The shapes of the continuum spectra are qualitatively similar to those expected for electron shake-off. However, the probabilities for electron shake-off as calculated from single-electron wave functions are much smaller than found experimentally. It is suggested that a many-body solution which explicitly includes electron correlations may be necessary. For example, such a calculation by Salpeter and Zaidi, for the case where one electron goes to the continuum while the other goes to the $2s$ state in the photo-ionization of He, is shown to be in good agreement with experiment. Some results are also presented on the differential cross sections of Ne and Ar for C $K\ensuremath{\alpha}$ x rays.

Fluctuations in total neutron cross-sections of Na, Al, Si, P, S in the energy interval (5.0÷8.5) MeV

Fluctuations in total neutron cross-sections of Na, Al, Si, P, S in the energy interval (5.0÷8.5) MeV