Np Transitions Research Articles

Optogalvanic detection of 7s-nP transitions in cesium

Using a single frequency ring laser with styryl-9 in the wavelength region 790 to 890 nm, optogalvanic signals of the 7s- nP transitions have been observed with excellent signal-to-noise ratio, making a frequency stabilization to one of these atomic transitions possible.

Excitation of rubidium atoms by electron impact

An analytic central potential containing two adjustable parameters is used to generate wave functions for the ground and excited states of the rubidium atom. The two parameters are chosen so that the potential reproduces accurately known values of optical oscillator strengths for the 5s−np (n≧5) transitions. Using the Born approximation, we calculate generalized oscillator strengths and integrated cross sections up to 5 keV for the 5s−np excitations. Reasonable agreement with experimental data is obtained.

Determination of Total Absorption of Na3S → nP Transitions for 5 ≦ n ≦ 28

Total absorption measurements of Na3S → nP transitions up to a main quantum number n = 28 have been performed at Na number densities in the range ≈ 1016 - 1017 cm-3 and temperatures ≈ 700-800 K. A heat pipe oven has been applied as an absorption tube in a single beam optical arrangement; experiment and data acquisition have been controlled by a computer. The results are compared with calculations using special assumptions with respect to line broadening mechanisms. The effect of binary and three-body collisions on total absorption is studied in detail. Within the pressure and main quantum number range investigated here a transition between the two types of interaction was demonstrated.

Electron impact excitation of Fe XXVI and other one-electron ions

It is shown that Coulomb-Born-Oppenheimer cross sections are in close agreement with distorted-wave results for 1s to np transitions in hydrogenic ions with Z>or=6 at all energies. Results are given for n=2, 3, 4, 5, 6 in Fe XXVI and compared with Coulomb-Born values. Results are also given for the 1s-2s transition at selected values of Z(2<or=Z<or=26). The results are intended for use in planned solar-maximum mission experiments.

Observation and interpretation of the photoionization cross section of the neutral iron atom (Fe I)

The relative photoionization cross section of the neutral iron atom has been determined in the region 1575 to 1150 AA using a crossed-beam photoelectric technique. The resonances observed below 1400 AA have been interpreted as being due to transitions of the type (3d6 5D)4s2 to 3d54s2np (n=4 and 5). Hartree-Fock and intermediate-coupling calculations of the structure of the 3d54s2np configurations have been carried out and the interpretation has been based on calculations of the transition probabilities for the 3d to np excitations. Resonances observed in the region between the first ionization limit at 1575 AA and 1400 AA are interpreted as due to (3d6 5D)4s2 to (3d6 5D)4s 4D np transitions.

Atomic parameters and rate coefficients for selected transitions in A1(XII)

Improved values for the electron impact excitation Gaunt factor, cross section and rate coefficients are obtained in the distorted wave approximation for the 1 s→ np and 2 s→ np ( n ⩽ 5) transitions in A1(XII). Also presented are the results of calculations for the oscillator strength for these transitions.

Oscillator strengths and photodissociation cross sections for Li 2+ and Na 2+

Electronic transition moments and oscillator strengths for three valence transitions in Li 2 + and in Na 2 + have been computed as a function of internuclear distance using wavefunctions obtained from a model potential description. Band oscillator strengths and photodissociation cross sections for the X 2Σ g +- 2Π u, X 2Σ g + - 2Σ u +( ns) and X 2Σ g + - 2Σ u +( np) transitions where n = 2 and 3 for Li 2 + and Na 2 +, respectively, are presented.

Electron impact excitation of H and He+. III. 1s to np transitions

For pt.II see abstr. A47878 of 1974. The distorted wave polarized orbital models described previously are used to calculate total and differential cross sections for 1s to np (n-2,3,4) transitions in H and He+. The calculated total 2p cross sections agree with experiment within +or-10% at all energies above 20 eV. Differential cross sections for total n=2 excitation are in good agreement with experiment at 50 eV and angles below 60 degrees . The predictions for 90 degrees polarization of Ly alpha also agree closely with experiment for E>or=20 eV.

Self consistent calculation of dynamic multipole polarizabilities and excited state wave functions of open shell ions: Li sequence

AbstractA variational formulation of the Hartree–Fock–Roothaan (HFR) theory for open shell ions in presence of time dependent perturbations is presented. The theory has been used to calculate the dynamic polarizabilities of the first three ions of the Li sequence. The polarizability values, extrapolated to zero frequency, show good shell by shell agreement with the corresponding static results. The polarizability graphs display resonance behaviour at the transition frequencies of the ions, and a study of these points leads to analytic HF wave functions for their low lying excited states. The calculated transition frequencies are in excellent accord with the experimental values. The calculated oscillator strengths for the 2s → np transitions are in reasonable agreement with the extensive multiconfiguration calculations of Weiss and the available experimental results.

Model potential calculations of sodium and potassium oscillator strengths

Oscillator strengths are computed for the 3s- np ( n = 3, 4,…, 15) transitions of sodium and for the 4s- np ( n = 4, 5,…, 16) transitions of potassium. By consistently including the effect of core polarization, excellent agreement between the present model potential calculations and experimental measurements is obtained and the discrete oscillator densities for the higher members of the principal series extrapolate smoothly to experimentally determined values near or at the series limit. The sensitivity of the results to the precise form of the core polarization correction near the origin is considered in detail.