Theoretical dielectronic recombination rate coefficients for ground-state hydrogen-like neon

Dielectronic recombination rate coefficients are calculated and presented for ground-state hydrogen-like neon as a function of electron temperature. Doubly excited nl n′l′ configurations of intermediate resonance states are restricted to n, n′ = 2, 3, and 4 with all allowed values of l and l′. Computations have been performed in intermediate coupling with configuration interaction.     

Radiative recombination of ions and nuclei in electron cooling systems

Experimental data on rates for the radiative recombination of nuclei (from helium to uranium) and various ions in interaction with an electron beam in electron cooling systems are reviewed. An analysis of the experimental data has yielded the dependence of the radiative recombination rate on the relative electron energy appreciably differently than the theoretical models obtained earlier by H. Kramers and R. Schuch. In addition, it is shown that the radiative recombination rate of nuclei in the experiment depends on the transverse electron energy as T _?? ^?0.82 ,which is also different from the results of the calculations by the theoretical model proposed by M. Bell and J. Bell. Experimental data on the cooling of ions in intermediate charge states are analyzed and the dependence of the radiative recombination rate on the charge state of the ion (electron-shell configuration) is shown. For some ion charge states, the rate of the process is of a resonance character. Loss to radiative recombination in the electron cooling system of the NICA Booster is evaluated for the Au³²⁺, Au³³⁺, Au⁵⁰⁺, and Au⁵¹⁺ ion beams. Limitations imposed on the Au79+ beam lifetime by radiative recombination in the electron cooling system of the NICA Collider are analyzed. Possible ways to decrease the radiative recombination rate of nuclei by selecting the parameters of the electron cooling system for the NICA Collider are proposed.     

The vuv photoelectron spectra of atomic In and Tl

The photoelectron spectra of atomic indium and thallium have been obtained using a pseudo-atomic beam technique. Ionizations from the np, ns and (n ? 1)d shells (n = 5 for In and n = 6 for Tl) were observed using He(I) and HE(II) radiation. The (np)^?1 ionization results in a single ¹S₀ ionized state, whereas the (ns)^?1 and ((n ? 1)d)^?1 ionizations both result in states additional to those allowed for a one-electron ionization process. This is attributed to configuration interaction in the final ionized state.     

Search for correlation effects in theM 4, 5 N 4, 5 N 4, 5 Auger spectrum of xenon

TheM _{4, 5} N _{4, 5} N _{4, 5} Auger spectrum of xenon has been measured with high resolution. Theoretical line intensities and relative line energies for this spectrum have been calculated applyingjj coupling to the initial states and intermediate coupling and configuration interaction to the final states. Two facts indicate that correlation effects are only small in the present case: The application of configuration interaction gives only small changes in line intensities and the experimental line intensities are found to be in good agreement with theoretical results, calculated without configuration interaction.     

Ab Initio Calculation of the Lowest Singlet and Triplet Excited States of the N<Subscript>2</Subscript> Molecule

Ab initio calculations of the adiabatic potential curves and matrix elements of radial nonadiabatic coupling of the N₂ molecule for the states related to dissociation limits I–V were performed. The most important spectral characteristics of the adiabatic states agreed well with the available experimental and theoretical data. The diabatic states were constructed. The diabatic quantum defects and radial matrix elements of the configuration interaction of the dissociative and Rydberg configurations whose states converge to the ground state \(X^{2}\Sigma{_g^+}\) and the first electronically excited state A²Π_u of the \(\rm{N_2^+}\) ion were calculated. The possibility of using the results for calculating the cross sections and rate constants of dissociative recombination and associative ionization within the framework of the multichannel quantum defect theory was discussed.     

Dielectronic recombination rates for the Be sequence

The dielectronic recombination (DR) rate coefficients have been recalculated for the C, Ar, and Fe target ions of the Be-sequence with an improved estimate of the high Rydberg state contribution. The Δn = 0 excitation-capture mode is reexamined in an improved LS coupling scheme and the effect of configuration interaction in the target and in the final (stably, bound) states is considered. The contribution of the 1s (Δn_t ≠ 0) excitation mode is also estimated and found to be on the order of 5% of the total DR capture rate at high electron temperatures. This updates and supersedes our earlier results for this isoelectronic sequence.     

New meson configuration in the bag model (I). First order energy spectrum of qqg states

Perturbative QCD in the bag is applied to unconventional configuration of quarks and gluons. The meson spectrum is computed to second order in the strong coupling. Exotic states with J^PC = 1^?+, 0^+?, 0^?? are found in the energy range 1.57 ? E ? 1.93 GeV.     

Rotational and vibrational states in 115Te

High-spin states of the ¹¹⁵Te were studied by in-beam spectroscopy with the ⁸⁹Y (²⁹Si, p2n) fusion-evaporation reaction at a beam energy of 108 MeV. γ?γ coincidence and γ?γ angular correlation analyses were employed for determining the level scheme of ¹¹⁵Te. We have identified two vibrational-like bands built on the νh_11/2 and νg_7/2 quasiparticle states and the noncollective oblate states from the full alignment of quasiparticle configurations. In addition, a regular ΔI = 2 sequence with positive-parity was found for the first time in odd-A Te nuclei. This sequence is interpreted as a deformed structure resulting from three-quasiparticle alignment having the [π(g_7/2, h _11/2) ? ν(h _11/2)] configuration. Calculations of total Routhian surfaces and cranked shell model were performed and were used for assigning quasiparticle configurations to the states in ¹¹⁵Te.     

Detailed study of the cluster structure of light nuclei in a three-body model: (II). The spectrum of low-lying states of nuclei with A = 6

The three-body α + 2N model developed in our earlier works to describe the ground states of the A = 6 nuclei is generalized here to describe the spectrum of the low-lying states of these nuclei. The levels of the nuclei are shown to be differently sensitive to the various Nα interaction components, whence some conclusions concerning the true form of the Nα interaction are drawn. The geometric structure of the ⁶Li and ⁶He ground states is studied in detail. A significant contribution of the stretched cigar-shaped three-particle configuration NαN with an α-particle between two nucleons has been found. The wave functions of the ground and excited states of the A = 6 nuclei are tabulated. The wave functions found have been tested carefully using numerous experimental data.     

A study of the 99Tc(p,d)98Tc reaction

The energy levels of ⁹⁸Tc were studied with the ⁹⁹Tc(p, d)⁹⁸Tc reaction at a bombarding energy of 22.9 MeV and 15 keV resolution (FWHM). The Q-value for this reaction was found to be ?6.755 ± 0.009 MeV and the ⁹⁸Tc mass excess was calculated to be ?86.421 ± 0.011 MeV. This reaction provided the excitation energies for 49 neutron hole states below 1.5 MeV excitation. Comparison of experimental angular distributions with DWBA calculations permitted assignment of lf-values and the extraction of spectroscopic factors for 44 of these levels. Extensive configuration mixing is observed except in the low-lying multiplet. Effective proton-particle, neutron-hole interaction matrix elements were obtained from the low-lying positive-parity multiplet of ⁹⁸Tc.     

Nuclear levels in166Ho: Evidence for a large configuration mixing

Fifty-six levels in¹⁶⁶Ho have been observed up to an excitation energy of 2,000 keV using the¹⁶⁷Er(t,α)¹⁶⁶Ho reaction with 17.0-MeV tritons. An anomalously small spectroscopic factor for the states in the [411↑±633↑] configuration has been observed, which has been interpreted as evidence for a large amount of configuration mixing with the states in the [523↑±521↑] configuration. Residual interaction calculations with a finite range central force have failed to account for the large configuration mixing observed. New assignments for 29 rotational states have been proposed. An anomalous singlet-triplet splitting is observed in the [404↓±633↑] configuration.     

Energy levels of the nucleus248Bk

The ambiguities and contradictions in presently available experimental information on the energy levels of the doubly odd deformed nucleus²⁴⁸Bk are sought to be cleared through calculation of the band head energies of the two-particle states based on evaluation of the residualn-p interaction energy for a zero range interaction. The applicability of the Gallagher-Moszkowski rule for the relative ordering of the spin triplet and singlet states is critically examined. It is concluded that the 8^? state from the {7/2⁺[633]p; 9/2^?[734]n configuration is the long lived isomer and forms the ground state of this nucleus. The 1^? state of the same configuration is the short lived isomer and an excited state in accordance with the GM rule and so is the 6⁺ state of the {3/2^?[521]p; 9/2^?[734]n configuration. The expected location of 20 two particle states comprising 10 GM pairs is calculated and compared with the available experimental information.     

Observation of resonance recombination lines in electron excited auger spectra of Gd

Combined measurements of electron excited N_4,5 Auger spectra and photoelectron emission on clean and oxidized Gd lead to a distinction between Auger lines originating from 4d → continuum and 4d → 4? resonance excitations. Several Auger structures are identified as due to the direct recombination of 4d⁹4?⁸ states with the 4f and valence electrons. The shape of the most prominent Auger line for oxidized Gd agrees perfectly with the Fano profile of the 4? photoemission intensity.     

A low-lying resonance in the spectrum of H

It was proved by Pekeris⁽¹⁾ that the singly excited states of H^- lie exactly at, or slightly above, the ground state of hydrogen. Using a theory of Fano,⁽²⁾ these fictitious states will have a configuration interaction with the H^- continuum. The strength of this configuration interaction is computed for the mixing of a 1s2p¹P⁰ state with the H^- continuum for different values of the fictitious binding energy of the 2p valence electron. In every case, the effect of the configuration interaction is to induce a rapid change of the phase shift of the continuum wave function by a quantity of π/2 over an energy range of a few times 0.01 eV, at an energy somewhat above the hydrogen ground state. The variation from π/2 to π is much slower. Such a swift change of the phase shift may be identified with the occurrence of a low-lying shape resonance.     

Pulsed dephotolysis in emulsion nanocrystals of silver halides: I. Recombination processes at early stages of photolysis

Early stages of formation of few-atom clusters of photolytic silver in AgBr nanocrystals are studied using the pulsed dephotolysis technique. It is shown that dephotolysis is characterized by a clearly pronounced dependence on the pulse duration of nonactinic and actinic radiations, the highest efficiency of dephotolysis being achieved for nanosecond pulses. The rate constant of recombination of free electrons with captured holes is determined (κ_p = (6 ± 1) × 10^?9 cm³ s^?1) and the dependence of the recombination rate on the level of excitation is found. The maximum recombination rate for the highest excitation level is found to be V _p ^max = 10⁹ s^?1 and the surface concentration of recombination centers is determined to be N _r = (2 ± 0.5) × 10¹¹ cm^?2.     

Photoionization and electron–ion recombination of Cr I

Using the unified method, the inverse processes of photoionization and electron–ion recombination are studied in detail for neutral chromium, (), for the ground and excited states. The unified method based on close-coupling approximation and R-matrix method (i) subsumes both the radiative recombination (RR) and dielectronic recombination (DR) for the total rate and (ii) provides self-consistent sets of photoionization cross sections σ_PI and recombination rates α_RC. The present results show in total photoionization of the ground and excited states an enhancement in the background at the first excited threshold, state of the core. One prominent phot-excitation-of-core (PEC) resonance due to one dipole allowed transition (⁶S-⁶P^o) in the core is found in the photoionization cross sections of most of the valence electron excited states. Structures in the total and partial photoionization, for ionization into various excited core states and ground state only, respectively, are demonstrated. Results are presented for the septet and quintet states with n≤10 and l≤9 of Cr I. These states couple to the core ground state ⁶S and contribute to the recombination rates. State-specific recombination rates are also presented for these states and their features are illustrated. The total recombination rate shows two DR peaks, one at a relatively low temperature, at 630 K, and the other around 40,000 K. This can explain existence of neutral Cr in interstellar medium. Calculations were carried out in LS coupling using a close-coupling wave function expansion of 40 core states. The results illustrate the features in the radiative processes of Cr I and provide photoionization cross sections and recombination rates with good approximation for this astrophysically important ion.     

Population of 2p 55s levels of neon in He-Ne plasma: I. The evolution of mechanisms in the discharge and the afterglow

The spectroscopic study of population processes of neon 2p ⁵5s states was carried out in helium afterglow with small admixture of neon at PHe = 38.1 torr, [He]/[Ne]=10^?5 with pulsed discharge afterglow in helium with small admixture of neon (pressure equal to 38.1 mm Hg; ). It is established that the main mechanism of population of 3s ₂ level (in Paschen’s notation) in the discharge and the initial after-glow is the excitation transfer from metastable atoms of He(2¹ S ₀). The other three levels—3s ₃, 3s ₄, and 3s ₅—corresponding to 2p ⁵5s configuration are populated in the afterglow as a result of the dissociative recombination HeNe⁺ of ions with electrons. The same process is also the main channel of population of 3s ₂ level in the late afterglow phase, when the concentration of He(2¹ S ₀) atoms is small. The hypothesis of recombination mechanism is confirmed by observation of the response of line intensities to pulsed electron heating. The partial coefficients of dissociative recombination into 2p ⁵5s states are estimated.