3p-3d Transitions Research Articles

A Theoretical Survey of 4s–4p and 4p–4d Transitions in Nickel-Like Ions

AbstractMulticharged ions in the isoelectronic sequence of nickel have a current interest, due to possible population inversions occuring between excited levels. The identification of 4s-4p and 4p-4d transitions was recently extended up to Mo XV, owing to new experiments performed at I.S.A.N., Troitsk (USSR), and to the subsequent interpretation of the first excited configurations by means of the Slater-Condon method and generalized least squares fit of energy parameters along a sequence. For predicting transitions in higher charge states, the same configurations have been studied ab initio by using the relativistic parametric potential method and selected transitions involving short-lived lower levels are given for 14 ions in the sequence from Sr XI to Eu XXXVI.

Wavelengths and Energy Levels for n = 3 − 3 Transitions in F-Like Ions: Cr XVI, Fe XVIII, Ni XX and Cu XXI

AbstractOn our beam-foil spectra recorded between 100 and 350 Å, we have identified the strongest 3s-3p and 3p-3d transitions of Cr XVI, Fe XVIII, Ni XX and Cu XXI. The Is22s22p53∓level energies have thus been deduced.

Wavelengths of the 3p-3d Transitions of the Co- and Fe-LIKE Ions: The Effects of Electron Correlation

AbstractThe experimental observations of the 3p63d92D – 3p53d102P transitions of the Co-like ions and 3p63d83F4– 3p53d93F3of the Fe-like ions have recently been extended to highly charged ions of heavy elements up to uranium (Z = 92). A comparison between the observed energies and calculated values from the Dirac-Fock model indicated persistent discrepancies of 3–4 eV for all ions. Systematic multiconfiguration Dirac–Fock calculations for these transitions have been carried out with emphasis on the effects of electron correlation. The previously found discrepancies between theory and experiment have mostly been removed after the inclusion of the electron–electron correlation effects in the theoretical calculations.

Breakdown of Dipole Selection Rules in Electron-Excited 3p-3d Transitions within Localized Transition-Metal Ions at Low Incident Energies

Metal M 2,3 inner-shell electron-energy-loss spectra in layered transition-metal tri-thiophosphates MPS 3 (M=Mn, Fe, Ni) have been measured at low incident energies in reflection geometry. The spectra reveal the multiplet structures of the final states of localized divalent metal ions. The relative intensities of the peaks are varied systematically as incident energy decreases. Large deviation from the X-ray absorption spectra are found at low incident energies. The variations are interpreted in terms of the incident energy dependence of momentum transfer involved in the inelastic scat-tering process and exchange interaction between incident and target electrons. It is found that dipole selection rules are broken in 3p-3d transitions within the localized 3d transition-metal ions as incident energy approaches the excitation threshold.

Stark broadening and regularities of prominent multiply ionized nitrogen spectral lines.

Stark widths of four N ii, fourteen N iii, five N iv, and two N v spectral lines have been measured in a linear-pinch discharge plasma and compared with existing experimental and theoretical results. Electron densities determined with single-wavelength laser interferometry with use of the visible 632.8-nm transition of a He-Ne laser cover the range of (0.40--1.80)\ifmmode\times\else\texttimes\fi{}${10}^{23}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$. The electron temperature of 50 000 K was determined from the Boltzmann slope of several N iii spectral lines, and from the relative intensity ratios of several N ii to N iii and N iii to N iv spectral lines. Since the majority of investigated N iii spectral lines originate from the 3s-3p and 3p-3d transition arrays, the Stark-width (w) dependence on the upper level ionization potential (I) of corresponding lines belonging to these two transition arrays was discussed and found to be of the form w=${\mathrm{aI}}^{\mathrm{\ensuremath{-}}b}$, where a and b are constants independent of the ionization potential. Similarly, the overall Stark width trends, using data obtained from the 3s-3p transition of the N ii, N iii, N iv, and N v spectral lines, were determined and discussed including the influence of emitter net charge on the Stark broadening dependence on the upper-level ionization potential. The established overall trend was used to predict the Stark width of uninvestigated spectral lines originating from the given 3s-3p transition with an accuracy better than 30%.

Population inversions in C iv in a recombing theta-pinch plasma

Population inversions on the 5g-4f and 4f-3d transitions of C IV at 253.0 and 116.9 nm have been observed in the recombination phase of a theta-pinch plasma initially containing 14 mTorr of acetylene and 0.5 mTorr of hydrogen gas. Population ratios of 17:11:1 for the 5g, 4f, and 3d levels were deduced from measured absolute line intensities of the 5g-4f and 4f-3d, and 3d-2p transitions at 253.0, 116.9, and 38.4 nm. The resulting gain-length product for a single pass through the 23-cm-long plasma column, based on the measured Doppler-broadened linewidth, is 2.3% at 116.9 nm and 5.8% at 253.0 nm.

A theoretical survey of 4s-4p and 4p-4d transitions in nickel-like ions through Sn XXIII

The predictions of 4s-4p and 4p-4d transitions derived from Slater-Condon type calculations of 3d9 4s, −4p and −4d configurations in the sequence Zn III-Se VII have been recently confirmed experimentally through Mo XV. These new data are used here to refine the predictions in the sequence Mo XV-Sn XXIII. The radial parameters involved in the three configurations are determined in generalized least-squares fits using all known levels in the sequence.

Electron energy loss spectra of SmCo5 and Nd2Fe14B films

Electron energy loss spectra (EELS) have been obtained on SmCo5 and Nd2Fe14B film samples for losses in the range from 0 to 80 eV. The SmCo5 samples investigated were sputtered samples that exhibited in the film plane static energy products of 15–20 MG Oe and coercivities in the 15–25 kOe range. The Nd2Fe14B samples were also sputtered films with coercivities of 15 kOe. The EELS spectra were obtained by using a 200-eV primary electron beam and then energy analyzing the backscattered electrons with a cylindrical mirror analyzer. Transition-metal (TM 3p-3d) and rare-earth (RE 5s-4f, RE 5p-5d, and RE 4f-5d) transitions were readily observed. It was also observed that the Sm 4f electrons in SmCo5 were more localized than the Nd 4f electrons in Nd2Fe14B from the RE 5s-4f transition which was consistent with the observed superior anisotropy field in the SmCo5 lattice. In contrast, the Fe in Nd2Fe14B was indicated to be more localized than the Co in SmCo5 as deduced from the TM 3p-3d transitions which suggested a weaker d electron polarization cloud in Nd2Fe14B and thus leading to a lower Curie temperature than SmCo5.

MCD spectroscopy and magnetization studies of matrix-isolated aluminium atoms

The electronic absorption spectra and magnetic circular dichroism (MCD) spectra of matrix-isolated aluminium atoms have been studied with particular reference to the 3p4s and 3p3d transitions. The g values of the isolated atoms also have been measured via the MCD magnetization technique. It is found that, in all matrices, the orbital angular momentum of the atom is heavily quenched giving g values very near 2.0. A consistent analysis of this phenomenon and of the spectra has been developed using a model in which the surrounding noble gas atoms exert an electrostatic field upon the aluminium atom and also enter into molecular orbital formation with it. This interpretation leads to the conclusion that the spin-orbit coupling of the optical electron is negative in both ground and excited states for Al/Kr and Al/Xe, but in the excited state only for Al/Ar. These results confirm and extend the findings of earlier EPR measurements.

On the 3s-3p and 3p-3d Transitions in Ne-like Ni XIX

An experimental and theoretical study has been made of the 3s-3p and 3p-3d transitions in Ni XIX. The method of beam-foil spectroscopy, using 30-64 MeV Ni ions from a tandem accelerator, has been combined with theoretical calculations using the multiconfiguration Dirac-Fock (MCDF) program.

Stark widths and shifts of Ne II spectral lines.

Stark widths and shifts of the most prominent Ne ii spectral lines originating from 13 multiplets have been measured and compared with existing experimental and theoretical results. A linear pinch discharge was used as a plasma source. Electron densities determined with single-wavelength laser interferometry using the visible \ensuremath{\lambda}=632.8 nm transition of a He-Ne laser cover the range of (0.30--1.42)\ifmmode\times\else\texttimes\fi{}${10}^{23}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$. The electron temperature, in the range of 22?0--40?0 K, was determined from the Boltzmann slope of several Ne ii spectral lines and from the relative intensity ratios of several Ne i--Ne ii lines. Experimental Stark width data of Ne ii spectral lines agree well with existing experimental and theoretical results. Stark shift experimental data disagree with existing theoretical data in some cases up to factor of 3. Our data and those of other authors were used to investigate the nature of Stark broadening and shift dependence on the upper-level ionization potential of the corresponding spectral line belonging to 3s-3p and 3p-3d transition arrays and to the np-nd Ne ii, Ar ii, Kr ii, and Xe ii homologous sequence.

MAGNETO-MODULATION REFLECTIVITY SPECTRA OF BixGd3-xFe5O12 BETWEEN 4 AND 20eV

With the synchrotron radiation, a transverse magneto-optical effect in bismuth substituted gadolinium iron garnets was measured by a reflection method. Differences of resonance energy shifts between the lights polarized parallel and perpendicularly to the direction of magnetization of the material were determined on reflectivity peaks in the near ultraviolet and a peak at the photon energy of about 18 eV. This reflectivity peak at about 18 eV was assigned to the 3d-4p transitions of iron ions in the octahedral and tetrahedral sites. A mechanism of the transverse magneto-optical effect in the 3d-4p transitions is discussed.

Identification of lines of ions belonging to the F i isoelectronic sequence for rubidium, strontium, and yttrium

In this Communication, we present wavelengths and identifications for 11 x-ray lines that are due to 2p–3d and 2p–3s transitions in Rb xxix. We also identify one of the strongest of the 2p–3d transitions in Sr xxx and Y xxxi. The x-ray spectra were obtained from laser-produced plasmas and are recorded on film. The Soreq laser facility in Yavneh, Israel, was used to generate the plasmas.

Electron collisional excitation in F-like selenium.

Electron collisional excitation of the low-lying 1${s}^{2}$2${s}^{2}$2${p}^{5}$ and 1${s}^{2}$2s2${p}^{6}$ states of F-like selenium to the singly excited M-shell states is studied using a relativistic distorted-wave model and multiconfigurational relativistic Hartree-Fock bound states. Results are presented for all 2-3 transitions from the low-lying 2${s}^{2}$2${p}^{5}$ $^{2}\mathrm{P}_{3/2}$ and $^{2}\mathrm{P}_{1/2}$ levels, and also the 2s2${p}^{6}$ $^{2}\mathrm{S}_{1/2}$ level. We find a number of strong dipole-allowed 2p-3d cross sections with peak values near threshold in excess of ${10}^{\mathrm{\ensuremath{-}}20}$ ${\mathrm{cm}}^{2}$, and derive Gaunt factors which are in good agreement with values used in the literature (0.15--0.20) for most strong transitions.Very strong monopole 2p-3p excitation cross sections have been important in soft-x-ray laser theory, and are found to be as strong as the largest dipole-allowed cross sections for F-like selenium. Theoretical output powers for the strong lines of the 2p-3s, 2p-3d, and 2s-3p transition arrays are computed and presented for plasma conditions of ${N}_{e}$=3\ifmmode\times\else\texttimes\fi{}${10}^{20}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ and ${T}_{e}$=1.0 keV. These results are compared in detail for proportionality against gf values for each array separately, as a test of how well line intensities might be judged from gf values in the absence of detailed theoretical intensity results. We find that for the 2p-3s and 2p-3d arrays, the intensities are in fair agreement with gf values within the array, while the agreement is much poorer in the case of the 2s-3p array. The two weaker arrays 2p-3s and 2s-3p are found to radiate more per unit gf than the 2p-3d transition array, in agreement with earlier observations in the Ne-like sequence. Theoretical line positions are tabulated for all strong 2-3 lines, and found to be in good agreement with experimental results for most strong transitions. Gains on the 3-3 transitions in between 2 and 4 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ are predicted for four lines under the plasma conditions quoted. Such conditions are similar to those of the recent extreme-uv laser experiments at the Lawrence Livermore National Laboratory, yet no F-like 3-3 amplification has yet been observed for F-like transitions. The discrepancy is currently a mystery.

3s-3p and 3p-3d Lines in Neonlike Sc XII, V XIV, Cr XV and Mn XVI Observed in Laserproduced Plasmas

Spectra from laserproduced plasmas of scandium, vanadium, chromium and manganese have been recorded in the region 200-600 Å. All the principal lines of the 3s-3p and 3p-3d transition arrays in the neonlike ions of these elements have been identified. Isoelectronic regularities of the wavenumbers have been studied, and the observations are compared with predictions from Dirac-Fock calculations.

Spectrum of sodiumlike selenium: Se xxiv

High-resolution spectra of Se xxiv have been obtained with a 3-m grazing-incidence spectrograph. Thin plastic foils coated with selenium were irradiated with four or eight beams of the OMEGA laser in a line-focus configuration. Spectrograms were obtained by viewing the plasma axially. Prominent in the spectra were the 3s–3p and 3p–3d transitions in the 150–240-Å region and the transitions nl–(n + 1)l′ with n = 3, 4 in the 24–80-Å region. We also present the energy levels and ionization limit derived from the measured wavelengths.

Energy-Level Scheme and Oscillator Strengths for the 3s-3p and 3p-3d Transitions in Silicon Sequence for Elements Vanadium Through Nickel

The HXR self-consistent field calculations of wavelengths and transition probabilities previously reported along the silicon sequence for elements K to Ti are extended to the 3s-3p and 3p-3d transitions of elements V to Ni. Ab initio HXR values of Slater parameters have been adjusted by a leastsquare optimization process of the calculated eigenvalues of the Hamiltonian with the available experimental energy levels. New accurate wavelengths and transition probabilities have been derived and six new identifications of solar lines are proposed.

Extended Analysis of Br VIII and Predicted Trends for the n = 4, Δn = 0 Transitions of Nickel-like Ions (Kr IX-Mo XV)

More than one hundred lines of Br VIII have been classified in the spectral region 416-824 Å, from which all levels of 3d94d (except 1S0) have been found. The energy levels of the configurations 3d94s, 3d94p and 3d94d have been interpreted from Zn III to Mo XV by means of the Slater-Condon theory and of generalized least squares techniques and the root mean square deviations are 8, 51 and 40 cm-1 respectively. The strongest lines of the 4s-4p and 4p-4d transitions are predicted from Kr IX to Mo XV.

Estimated gains for a Ni-like exploding foil target

It is shown that an exploding Eu foil target irradiated with 7.5×1013 W/cm2 should reach plasma parameters which look optimistic for soft x-ray lasing. Among the lines of interest are two 4p-4d transitions near 100 Å and two near 80 Å with gains estimated at 4–7 cm−1.

The 2p53s, 3p and 3d Configurations in Neon-Like Ca XI

The calcium spectrum emitted from a laserproduced plasma has been recorded in the region 250-700 Å. By means of relativistic ab initio calculations and isoelectronic interpolations, 24 lines have been identified as 3s-3p and 3p-3d transitions in neon-like Ca XI. The charge state identifications were confirmed by the characteristic shape of the Ca XI lines. The structure of the 2p53s, 3p and 3d configurations has been analysed by means of fitted energy parameters and scaled integrals from Hartree-Fock wave functions.