R. E. Olson

Ab initio calculations for the X 2Σ, A 2Π, and B 2Σ states of NaAr: Emission spectra and cross sections for fine‐structure transitions in Na–Ar collisions

Configuration interaction (CI) calculations were performed for the X 2Σ, A 2Π, and B 2Σ states of NaAr. The A 2Π state is calculated to have a well depth of 492 cm−1 at an internuclear separation of 3.04 A. Small wells of 55 and 32 cm−1 were found for the X 2Σ and B 2Σ states located at 5.01 and 6.80 A, respectively. The spectra for A 2Π–X 2Σ emission in the limits of zero and infinite Ar pressure were calculated and compared with the experiment of York, Scheps, and Gallagher and the predictions using the pseudopotential curves of Pascale and Vandeplanque. The potentials from this work give spectra in much better agreement with experiment than the pseudopotential predictions. Total and differential cross sections for fine‐structure changing transitions Na(2P1/2) +Ar→Na(2P3/2)+Ar−17.2 cm−1 were calculated by a quantum mechanical technique. The total cross sections are in excellent agreement with experimental results. The excited state differential cross sections exhibit prominent rainbow structure centered...

Ion–Ion Recombination Total Cross Sections—Atomic Species

A multistate Landau–Zener method is set up for the calculation of atomic ion–ion mutual neutralization total cross sections. The results of the calculations are compared with experimental results for O++O−, N++O−, He++D−, He++H−, and H++H−. The energy range scanned depends on the system but varies between about 0.1 and 10 000 eV. The agreement between theory and experiment is usually within a factor of 2.

Coupled‐channel study of halogen (2P) + rare gas (1S) scattering

Quantum mechanical coupled‐channel (CC) scattering calculations are reported using realistic adiabatic potentials for the 2P+1S interaction of F–Ar, F–Xe, and Cl–Xe. Differential cross sections dσ/dω derived from a simple elastic approximation appropriate for large spin orbit interactions accurately reproduce all the gross features computed by the coupled‐channel method. This finding supports the extraction of interaction potentials from laboratory differential cross sections I (ϑ) via an elastic analysis. Integral inter and intramultiplet changing cross sections are expressed conveniently in terms of Grawert’s B(j, j’;g) coefficient. Information on the collision dynamics is extracted by following the partial wave dependence of selected B(j, j’;g). Classical turning point analysis, based on the values of the large l‐waves for which these partial wave contributions Bl(j, j’;g) begin to rise above zero, leads to the conclusion that both intermultiplet and first order forbidden intramultiplet transitions are...

Interaction energies for low‐lying electronic states of NaH and NaH−: Scattering of H− by alkali atoms

Extensive ab initio configuration interaction calculations have been performed for the seven lowest states of NaH and the four lowest 2Σ states of NaH−. Representative potential well parameters Re and De for the X 1Σ, A 1Σ, and C 1Σ states of NaH are 3.558 ao, 1.922 eV; 5.992 ao, 1.239 eV; and 11.88 ao, 0.787 eV, respectively. From the NaH− calculations, the adiabatic molecular electron affinity of NaH is found to be 0.373 eV. The molecular calculations on the low‐lying states of NaH− allow us to predict that the mechanism for low energy electron loss in the H−+Na→H°+... reaction is primarily due to interactions with the H°+Na− charge transfer state. Cross sections are presented fo the H−+Na, K, Rb, and Cs electron loss reactions.Extensive ab initio configuration interaction calculations have been performed for the seven lowest states of NaH and the four lowest 2Σ states of NaH−. Representative potential well parameters Re and De for the X 1Σ, A 1Σ, and C 1Σ states of NaH are 3.558 ao, 1.922 eV; 5.992 ao, 1.239 eV; and 11.88 ao, 0.787 eV, respectively. From the NaH− calculations, the adiabatic molecular electron affinity of NaH is found to be 0.373 eV. The molecular calculations on the low‐lying states of NaH− allow us to predict that the mechanism for low energy electron loss in the H−+Na→H°+... reaction is primarily due to interactions with the H°+Na− charge transfer state. Cross sections are presented fo the H−+Na, K, Rb, and Cs electron loss reactions.

Rainbow scattering for Ar+ + Ar and Xe+ + Xe☆

Elastic differential scattering measurements have been performed on Ar+ + Ar and Xe+ + Xe. The rainbow scattering angle is found at τ = Eθ ≈ 115 eV deg for Ar+2 and τ ≈ 93 eV deg for Xe+2. These data are consistent with a potential well depth of 1.25 eV for Ar+2 and 0.97 eV for Xe+2.

Elastic scattering measurements of the Ar2* (3Σ+u) well depth

Angular distribution measurements of the scattering of Ar(3P2) from Ar(1S0) at center of mass collision energies from 5 to 10 eV yield a prominent rainbow maximum at τ=Eϑ=81±3 eV‐deg. Combined with recent high energy ground state scattering data and information derived from the Ar2* emission continua, the result implies that De=0.78±0.04 eV and Re=2.33±0.02 A in an assumed Morse form for the lowest 1u, 0−u(3Σ+u)Ar2* excimer potential.

CI Potentials for the X 2Σ and a 2Π states of Ar+ + He

Configuration interaction (CI) potentials have been calculated for the ground X 2Σ and A 2Π molecular states of Ar+ + He. Both potentials are found to be weakly bound with the potential well characteristics for the X 2Σ state, Re = 4.71 a0 and De = 55.0 meV, and for the A 2Π state, Re = 5.65 a0 and De = 26.2 meV.

Energy dependence for Ne*(2p53s3P) + Ar ionization total cross sections

Abstract The ionization (Penning and associative) total cross sections for Ne * (2p 5 3s 3 P) + Ar are calculated semiclassically in the energy range of 0.001 to 1000 eV and compared with recent experimental results of Micha et al.

Interaction potential for the X1Σ state of Li+ + Ar

Abstract The ground state potential curve of LiAr + was calculated using the configuration interaction (CI) method. Analysis of computational errors and comparison with experimental differential cross section data yields σ = 3.66 ± 0.05 α o , R e = 4.44 ± 0.05 α o , and D e = 0.30 ± 0.01 eV for the potential well parameters.

Fine structure transition cross sections for several alkali + rare gas systems

The energy dependence, Ec.m. </ 0.2 eV, of the inelastic total cross sections for the 2P12 → 2P32 fine structure transition of the lowest excited states of the alkali atoms are calculated for the following systems: Na, K, Rb + He, Ne, Ar and Cs + He. Encouraging agreement between theory and experiment is obtained.