Electric Dipole Oscillator Research Articles

Multiplet Splittings and IS,3p, Intercombination-Line Oscillator Strengths in be i and MG I

view Abstract Citations (28) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Multiplet Splittings and IS,3p, Intercombination-Line Oscillator Strengths in be i and MG I Laughlin, C. ; Victor, G. A. Abstract Model potential methods are used to calculate electric dipole oscillator strengths and transition probabilities for 2sns `S0-2smp 3P1 transitions in Bei and 3sns `S0-3smp 3P1 transitions in Mgi. Comparison of predicted multiplet splittings and oscillator strengths with available experimental and theoretical data demonstrates that the procedures employed are capable of producing results of high accuracy. The calculated Mg 15o-353P 8P1 transition oscillator strength is 2.11 x 10-6. Subject headings: atomic processes - transition probabilities Publication: The Astrophysical Journal Pub Date: September 1974 DOI: 10.1086/153090 Bibcode: 1974ApJ...192..551L full text sources ADS |

Electric dipole transitions in the carbon isoelectronic sequence calculated with symmetric states obtained from superposition of configurations

Sinanoğlu's nonclosed shell many electron theory (NCMET) is used to determine and analyze symmetry-adapted correlated wavefunctions for states of the F(IV) ion belonging to the 1s 22s 22p2 and 1s 22s 2p3 configurations. We argue that these wavefunctions contain those specific correlation effects important in calculating accurate oscillator strengths for allowed transitions between states of these two configurations. The types of correlations included, the reasons for their importance, the methods of approximating them, and the necessity and techniques for introducing symmetry into these calculations are discussed. Comparison of results using Hartree-Fock as opposed to correlated wavefunctions clearly shows the necessity of including correlation effects in calculating the electric-dipole oscillator strengths in F(IV). The conclusion follows for both the dipole-velocity and the dipole-length formulations. These new results for the six electric-dipole transitions in F(IV) are combined with previously published results for the same transitions in the isoelectronic species C(I), N(II), O(III) in order to extrapolate the Z dependence of these transitions and thereby make reasonable predictions of the oscillator strengths for the heavier ions. We conclude with a formalism, based on plausible but as yet unproven speculations, which shows in a transparent way what correlation effects are of significance in the general problem of computing oscillator strengths.

Optical Intensities of Rare-Earth Ions in Yttrium Orthoaluminate

Optical absorption and emission intensities are investigated for trivalent rare earths in YAl${\mathrm{O}}_{3}$. Ions examined included Pr, Nd, Eu, Tb, Ho, Er, Tm, and Yb. Oscillation strengths of $f\ensuremath{\rightarrow}f$ transitions between $J$ manifolds were measured at room temperature and compared with calculated electric and magnetic dipole oscillator strengths. The Judd-Ofelt approach and phenomenological parameters for each ion were used to derive the electric dipole intensities. The intensity parameters, which were obtained for a least-square-fitting procedure, exhibited a general decrease with increasing number of $4f$ electrons throughout most of the series. The intensities for Pr and Tb were not satisfactorily accounted for in the present theory; some reasons for this are presented.

Systematic Trends in Atomic Oscillator Strengths: The Helium Isoelectronic Sequence

Electric dipole oscillator strengths (f values) have been calculated for a large number of singlet and triplet S–P, P–D, and D–F transitions in the helium isoelectronic sequence through O+6. The analytical orbital wave functions employed were of frozen-core type, and generally produce very good agreement between length and velocity values of the calculated oscillator strengths. A conspicuous exception occurs in many cases where the principal quantum number remains unchanged in the transition, and the more reliable dipole length values have been adopted for such transitions. The smooth variation of the calculated f values as functions of the inverse of the nuclear charge Z provided a sensitive check on the accuracy of the computations and indicated a considerable number of P–D transitions where the velocity values seemed the more reliable. Wherever comparison data are available, our calculated oscillator strengths are in excellent agreement with the most accurate values; in other cases, the absolute uncertainty in the f values should in no case exceed 5%.

Intercombination Oscillator Strengths in the Helium Sequence

view Abstract Citations (99) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Intercombination Oscillator Strengths in the Helium Sequence Drake, G. W. F. ; Dalgarno, A. Abstract The electric dipole oscillator strengths and transition probabilities of the spin-forbidden transitions among the 1'S, 21S, 21P, and 23P levels of the heliumlike ions from He i to Ne ix are evaluated to high accuracy by purely theoretical methods Publication: The Astrophysical Journal Pub Date: July 1969 DOI: 10.1086/150080 Bibcode: 1969ApJ...157..459D full text sources ADS |

Raman scattering by polaritons

In crystals lacking a center of inversion, polaritons participate in first order (one polariton) Raman scattering via electric-dipole excitation- and electric field-induced changes in the electric susceptibility. The electric-dipole oscillation and the electric field amplitudes of polaritons can be obtained, simply and directly, from the expression for the energy density of electromagnetic radiation in a dispersive dielectric medium and the relation between the electric-dipole oscillation and electric field amplitudes, which is obtained from the equations of motion. The magnitudes of the macroscopic electric field and the atomic displacement amplitudes of coupled plasmon-LO phonon modes are shown to be the same as the corresponding quantities of the coupled photon-TO phonon polariton modes having the same frequency.

Dipole properties of the metastable states of helium

A variational method is used to calculate the effective electric-dipole oscillator strength distributions of the ground and metastable states of helium. Accurate values are obtained of the refractive indices, the long-range interactions and the mean excitation energies controlling the absorption of a beam of fast charged particles.

Oscillator strengths of many-electron atoms

Transitions due to the valence electrons of many-electron atoms are considered. Results of various authors on electric dipole oscillator strengths are briefly discussed. Orientational calculations on Cr 3+ and other systems are presented.

Site Testing for EMP (Electromagnetic Pulse) Hardness

To answer questions about EMP hardness of shock-hardened sites, one might employ an electromagnetic diagnostic testing procedure. An idealized procedure is presented as a model for more realistic tests. The procedure is to determine the Green's or Transfer function of the site using infinitesimal electric and magnetic dipole oscillators. The Green's function is comprised of the set of measured electric and magnetic fields when the oscillators are operated at each point, with each orientation and frequency. It is shown how the fields within the site are predicted, given knowledge of the currents in air producing the EMP, or the tangential components of the fields on the earth's surface.

Symmetry of a colour centre in magnesium oxide

The symmetry of the centre responsible for the 9570 cm-1 (10 450 A) line, which appears in the absorption spectrum of neutron-irradiated magnesium oxide, has been investigated at 77 °K by analysis of the polarization spectra of the line under uniaxial stress. The line is associated with a [110] linear electric dipole oscillator in a centre which has orthorhombic symmetry and [110] orientation. The peaks in the phonon-assisted spectrum of the line can be explained by taking 280 cm-1 and 380 cm-1 as the energies of the fundamental phonon modes. There is some evidence for a second zero-phonon line at 10 070 cm-1 having phonon energies of 380 cm-1 and 490 cm-1.

Van der Waals Forces for the Inert Gases

Theoretical and experimental values of electric-dipole oscillator strengths for inert-gas atoms are analyzed to yield a set of oscillator strengths, which satisfy the Thomas-Kuhn sum rule, and which reproduce the experimental refractive indices and Verdet constants. These oscillator strengths are then used to calculate the long-range van der Waals interaction between all pairs of atoms selected from helium, neon, argon, krypton, and xenon. The derived interaction constants are probably in error by less than 10%. They disagree with the currently accepted values of the interaction constants.

Van der Waals Forces for Hydrogen and the Inert Gases

Experimental data and theoretical calculations on neon and argon are analysed to yield consistent sets of electric dipole oscillator strengths. The derived oscillator strengths are used with known values for hydrogen and helium to calculate the van der Waals energies between all pairs of atoms selected from hydrogen, helium, neon and argon. The results are summarized in the Table. The probable error is less than 10%.

Van der Waals Forces

Theoretical and experimental values of electric dipole oscillator strengths are used to calculate the coefficients of the leading terms in the series representations of the long range interactions between pairs of atoms. Values are obtained for pairs selected from the alkali metals, the inert gases, H, H-, He+ and Li+ and are then employed to assess the accuracy of various approximate formulae. Where possible, comparison is made with experimental data and it is shown that the polarizabilities derived from molecular beam measurements are unreliable. A discussion is given of the measurements of elastic scattering of the alkali metals by the inert gases and it is concluded that the normal van der Waals interaction does not suffice to explain the observations at very low scattering angles.

Relativistic Radiative Transitions

The relativistic electric dipole oscillator strengths at the series limit for K electrons in lead have been recomputed and discrepancies between published values resolved.Received 18 February 1957DOI:https://doi.org/10.1103/PhysRev.106.754©1957 American Physical Society