Cross section for the excitation of helium by protons

1979 ◽  
Vol 57 (8) ◽  
pp. 1174-1177
Author(s):  
S. P. Ojha ◽  
P. Tiwari
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Proton Impact ◽  
Experimental Findings

Cross sections for the singlet excitation of helium by proton impact have been computed using the Vainshtein, Presnyakov, and Sobelman (VPS) method with peaking approximation. Transitions from the ground state to the n1P(n = 2, 3, and 4) states have been taken into account. The results are compared with other theoretical and experimental findings.

scholarly journals Photoionisation Cross Sections of Chlorine Atoms and Molecules at 584 Å

1986 ◽  
Vol 39 (5) ◽  
pp. 779 ◽  
Author(s):  
WJ van der Meer ◽  
RJ Butselaar ◽  
CA de Lange
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Modulation Method ◽  
Absolute Cross Section ◽  
Molecular Chlorine ◽  
Chlorine Atoms ◽  
Atoms And Molecules ◽  
Ionic States ◽  
State Ionic

A recently developed modulation method is used to obtain cross sections for the photoionisation of ground state neutral to ground state ionic, atomic and molecular chlorine relative to that of the HCl + (X2n 1IZ,3IZ) +-- HCl(XI ~ +) transition at the He Ia wavelength. With the known absolute cross section of the latter process, determined by (e,2e) coincidence spectroscopy, the present ell,periments provide absolute photoionisation cross sections of the CI + epz,l,o) +-- Clep) and Cli (XZ n g, 1IZ,3 IZ) +-- Clz (X I ~ t) transitions. Relative cross sections, previously determined for the transitions to the additional Cl and Clz ionic states accessible with He Ia radiation, are used to obtain absolute cross sections for the Cl+(IDz, ISO) +-- Clep) and Cli(AZnu,1IZ,3IZ, BZ~t) +-- Clz(XI~t) ionisation processes.

scholarly journals Spatial Non-uniformity in Discharges in Low Pressure Helium and Neon

1987 ◽  
Vol 40 (3) ◽  
pp. 383 ◽  
Author(s):  
J Fletcher ◽  
PH Purdie
Keyword(s):  
Monte Carlo Simulation ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Low Pressure ◽  
Photon Flux ◽  
Cross Section Data ◽  
Section Data ◽  
Neon Gas ◽  
Wavelength Distribution

Low current, low pressure, steady state Townsend discharges in helium and neon gas have been investigated using the photon flux technique. Such discharges have been found to exhibit spatial non-uniformity resulting in luminous layers throughout the discharge. The separation and structure of these layers has been investigated experimentally in both gases along with the wavelength distribution of the photon flux. A Monte Carlo simulation of the discharge in neon has been used to gain information on the cross sections necessary to describe these discharges. It is found that direct excitaton of ground state atoms to the resonance level of each gas is less than indicated by some published cross section data.

QUASI-CLASSICAL TRAJECTORY STUDY OF THE REACTION PROBABILITY AND CROSS SECTION OF THE REACTION LiH + H

2013 ◽  
Vol 12 (01) ◽  
pp. 1250093 ◽  
Author(s):  
YULIANG WANG ◽  
JINCHUN ZHANG ◽  
BAOGUO TIAN ◽  
KUN WANG ◽  
XIAORUI LIANG ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Collision Energy ◽  
Energy Surface ◽  
Classical Trajectory ◽  
Reaction Cross ◽  
Reaction Probability ◽  
Title Reaction ◽  
Reaction Cross Sections

Based on the new accurate potential energy surface of the ground state of LiH2 system. Quasi-classical trajectory (QCT) calculations were carried out for the reaction LiH + H . The reaction probability of the title reaction for J = 0 has been calculated. The reaction cross sections were calculated as functions of the collision energy in the range 0.1–2.5 eV. The results were found to be well consistent with the previous real wave packet (RWP) and QCT results.

Erbium Doped Tellurite Glasses

1991 ◽  
Vol 244 ◽  
Author(s):  
Jau-Sheng Wang ◽  
Elias Snitzer ◽  
George H. Sigel
Keyword(s):  
Excited State ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Optical Transition ◽  
Emission Cross Section ◽  
Excited State Absorption ◽  
Tellurite Glasses ◽  
Ground State Absorption ◽  
Erbium Doped

ABSTRACTThe results to be presented focus on the optimization of tellurite glass compositions which are suitable both for doping with erbium oxide as well as subsequent for fiber drawing. The laser related properties, such as fluorescence spectrum, lifetime, and optical transition cross sections will be presented. Judd-Ofelt parameters for erbium in the glasses have been exploited to predict fluorescence lifetime, excited state absorption(ESA), ground state absorption(GSA) and ground state fluorescence(GSF). For comparison, the absorption cross section, emission cross section, excited state absorption(ESA)/ground state absorption(GSA)(0.8μm pumping) and fluorescence terminating in the ground state(GSF)/excited state absorption(ESA) ratios are calculated for both Al2O3-SiO2 and tellurite glasses.

Spin-Dependence of the Electron Scattering Cross Section by a Magnetic Layer System and the Magneto-Resistance

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3376-3380 ◽  
Author(s):  
J. T. Wang ◽  
F. Tang ◽  
W. D. Brown ◽  
D. Bagayoko
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Magnetic Layer ◽  
Bulk Sample ◽  
Scattering Cross Section ◽  
Layer System ◽  
Interfacial Roughness ◽  
Scattering Cross ◽  
Experimental Findings ◽  
Magneto Resistance

We present a theoretical model for calculating the spin-dependent cross section of the scattering of electrons by a magnetic layer system. Our model demonstrates that the cross sections of the scattering are different for spin up and spin down electrons. The model assumes that the electrical resistivity in a conductor is proportional to the scattering cross section of the electron in it. It is believed to support the two channel mechanism in interpreting magneto-resistance (MR). Based on the model without considering the scattering due to the interfacial roughness and the spin flipping scattering, we have established a relationship between MR and the square of the magnetic moment in the bulk sample without considering the scattering due to the interfacial roughness and the spin flipping scattering. It can also qualitatively explain the MR difference between the current in plane (CIP) and current perpendicular to the plane (CPP) configurations. The predictions by the model agree well with the experimental findings.

scholarly journals Cross Section Ionization By Electron Impact Of Helium Like Ions

2021 ◽  
Author(s):  
Manel Hariz Belgacem ◽  
Elhabib Guedda ◽  
Haikel Jelassi
Keyword(s):  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
The Cross ◽  
State 1 ◽  
Unstable States ◽  
Good Agreement

<sub></sub> In this paper we present our calculation of the cross section ionization by electron impact of C V, N VI and O VII. Using the Flexible Atomic Code (FAC), we obtain the cross sections for the ionization of these ions from the ground state 1<sup>1</sup>S, and from the unstable states 2<sup>1</sup>S and 2<sup>3</sup>S. Our results are in good agreement with those based on the Coulomb Born (CB) approximation and the available measurements.

Photoneutron cross sections in 7Li

1977 ◽  
Vol 55 (5) ◽  
pp. 428-433 ◽  
Author(s):  
H. Ferdinande ◽  
N. K. Sherman ◽  
K. H. Lokan ◽  
C. K. Ross
Keyword(s):  
Fine Structure ◽  
Excited State ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Reasonable Agreement ◽  
Branching Ratio ◽  
Energy Spectra ◽  
Average Value ◽  
First Excited State

Photoneutron energy spectra from 7Li have been measured by time-of-flight methods, for bremsstrahlung end-point energies increasing in 2 MeV steps from 13 to 25 MeV. The ground-state and approximate first-excited-state differential cross sections at 90° have been obtained from 8.5 to 23 MeV. No pronounced fine structure has been observed. The measured branching ratio to the first excited state falls from an average value of 0.70 between 10.3 and 14.5 MeV to an average of 0.29 between 14.5 and 18 MeV, and rises again to an average of 0.38 between 18 and 23 MeV. This behaviour can be explained by a crude theoretical model in which 1p → 2s and 1p → 1d single particle transitions dominate below 18 MeV. The calculation predicts a branching ratio of 0.50 near threshold, falling to 0.23 at higher energies, in reasonable agreement with the experiment. The integrated value of the ground-state cross section up to 23 MeV is about (38.7 ± 3.9) MeV mb, while that for the first excited state is about (17.2 ± 3.4) MeV mb. Together they account for 39% of the exchange-augmented dipole sum of 7Li.

scholarly journals Столкновения с участием поляризованных щелочных атомов цезия и лития

2020 ◽  
Vol 128 (4) ◽  
pp. 483
Author(s):  
В.А. Картошкин
Keyword(s):  
Magnetic Resonance ◽  
Frequency Shift ◽  
Temperature Dependence ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Resonance Line ◽  
Spin Exchange ◽  
Interaction Potentials ◽  
The Real

The cross section and frequency shift of the magnetic resonance line for the spin exchange are calculated for a collision of lithium and cesium atoms in the ground state. The calculation was carried out on the basis of data on the singlet (X1Sigma+) and triplet (a3Sigma+) interaction potentials of the 7Li133Cs dimer. The transfer from the energy to the temperature dependence of the real and imaginary parts of the complex cross sections for a spin exchange allows us to obtain information both the broadening of the magnetic resonance line of the atoms under study and the frequency shift of the magnetic resonance upon their collision.

Rotational Energy Transfer within the A1Σu+ State of Na2 Induced by Collisions with (2S1/2) Na

2007 ◽  
Vol 62 (3-4) ◽  
pp. 176-178
Author(s):  
Rami Haj Mohamad ◽  
Khaled Hussein ◽  
Abdel-Monhem Nachabé
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Rhodamine 6G ◽  
Rotational Energy ◽  
Spectral Lines ◽  
Rotational Energy Transfer ◽  
Rotational Transitions ◽  
Electronic Ground

The (v’ = 34, J’ = 14) level of the A1Σ+u electronic state of Na2 has been selectively populated by excitation with the 578.1 nm line of a ring dye-laser with rhodamine 6G. Through collisions with (2S1/2) Na atoms, energy is transferred to neighbouring rotational levels in Na2, and the density of these levels is determined by observing the fluorescence to the electronic ground state. From previous measurements of the lifetime of the A1Σ+u state and new measurements of the intensities of collision-induced spectral lines, absolute collision cross-sections for all rotational transitions up to ΔJ = ±6 have been obtained; the total cross-section for all rotational transitions observed is: rotσtotal = 0.41 nm2.

Cross section for the excitation of helium by He+

1978 ◽  
Vol 56 (9) ◽  
pp. 1232-1234
Author(s):  
S. P. Ojha ◽  
P. Tiwari ◽  
K. P. Srivastava
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Experimental Results

Cross sections for the singlet excitation of helium by He+ impact have been calculated under the Vainshtein, Presnyakov, and Sobelman (VPS) method with peaking approximation. Transitions from the ground state to the n1P(n = 2 and 3) states have been considered. The results are compared with other theoretical and experimental results.

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