Re-examination of the spectrum of strontium: autoionization in the spectrum of neutral strontium

Newsom, G. H.; O'Connor, Seamus; Learner, R. C. M.

doi:10.1088/0022-3700/6/10/028

Cited by 32 publications

(8 citation statements)

References 9 publications

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“…Particularly, as far as the Sr atom is concerned, the autoionizing states observed up to now belong to the odd configurations 4dnI (J = i) [2][3][4][5], 5 pnl (J = 1) [5][6][7], 4dnl (J=3) [8] and 5pnd (J=3) [9], while only the 4d5d (J=l-5) and a few 4d6d members of the even states are reported up to now [10].…”

Section: Introductionmentioning

confidence: 88%

Detection of the even parity,J=0–3, autoionizing 4dnl Rydberg states of strontium by two-step laser optogalvanic spectroscopy

Jimoyiannis

Bolovinos

Tsekeris

1992

Z Phys D - Atoms, Molecules and Clusters

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Abstract.We have measured the energies of a few hundreds of even parity, J = 0-3 autoionizing 4 d nl Ry states of strontium using an optogalvanic spectroscopy technique. These states are reached by a two-step pulsed dye laser excitation from the 4d 5s metastables through the 4d5p 3Po, 1, 2 intermediate states. Electronic collisions populate the 4d 5s states in a d.c. glow discharge through a Sr plus He vapour in a heated quartz cell. The electronic configuration for the majority of the observed Sr states is deduced from their quantum defect values and other characteristics of the corresponding transitions.

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Section: Introductionmentioning

confidence: 88%

Detection of the even parity,J=0–3, autoionizing 4dnl Rydberg states of strontium by two-step laser optogalvanic spectroscopy

Jimoyiannis

Bolovinos

Tsekeris

1992

Z Phys D - Atoms, Molecules and Clusters

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“…The J = 0 e autoionizing resonances below the 4d 5/2 threshold have been observed using two-photon or two-step laser spectroscopy from the 5s 2 ground state in an atomic beam (Kompitsas et al 1991); in particular, the broad 5p 2 1 S 0 resonance, with an autoionization width of roughly 230 cm −1 , was recorded at 54 451 cm −1 above the ground state. Some low-lying J = 2 e autoionizing resonances have been observed in the Sr arc spectrum by Newsom et al (1973). The 5p 2 1 D 2 autoionizing resonance was recorded using two-photon ionization spectroscopy (Ewart andPurdie 1976, Esherick 1977) and in photoionization from the 5s5p 1 P o 1 level (Mende et al 1995, Dai et al 1996.…”

Section: Introductionmentioning

confidence: 99%

EigenchannelR-matrix study of two-photon excitation of low-lying autoionizing states in strontium: dielectronic core-polarization effects

Luc‐Koenig

Aymar

Lecomte

et al. 1998

J. Phys. B: At. Mol. Opt. Phys.

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Two-photon ionization processes from the ground state of strontium are studied employing the jj -coupled eigenchannel R-matrix approach combined with the multichannel quantum-defect theory (MQDT). The calculations satisfactorily reproduce the experimental spectra corresponding to two-photon excitation of the 4d6d J = 0 e , J = 2 e and 5p 2 1 S 0 , 1 D 2 low-lying autoionizing resonances, confirming that the method is suitable to account for the spin-orbit interaction effects in the multiphoton excitation of heavy atoms. It is also shown that the dielectronic core polarization cannot be disregarded in the description of these highly correlated resonances, as it affects significantly both their energy positions and autoionization widths.

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“…Again, 3/2 no signal was present at X T =4715 A c We note that a narrow (<3 cm" 1 ), very weak component, J = 4-J = 4, of the Sr autoionizing multiplet Sr(4d5p 3 F°)-Sr(4d6d 3 F) has been reported at 4715 A. 19 The absence of any signal with the transfer laser tuned to the (thermalized) J = 3^J = 3 component at 4662 A makes it highly unlikely that the J = 4^ J = 4 component makes any contribution to the observed 4715-A signal.…”

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confidence: 60%

Laser-Induced Charge Transfer to an Excited Ionic State

et al. 1979

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total strength of 0.27 ji 0 2 which is quite comparable to experiment. At higher energies an additional strength of 0.6^0 2 is predicted to be fragmented over a number of levels. The groundstate wave function generated in this calculation has a 17% 2p, 2h intensity. On the other hand, the SU 3 shell-model calculations of Millener 9 predict only ~0.05ji 0 2 of ground-state Ml strength between 16 and 20 MeV. The total Ml strength is predicted to be weak because the ground-state correlations are predicted to be mainly of maximum spatial symmetry [4 4 ] and hence cannot be excited by the dominant (spin) part of the Ml operator, The present experimental results appear to require the 16 0 groundstate correlations to be mainly of lower spatial symmetry.In the future it will be interesting to search experimentally for Ml strength at higher energies in 16 0, although this will probably be appreciably more difficult,,We are pleased to acknowledge the help of R. Helmer, K. Lesko, and L. Stokes during parts of the data taking, and A. Arima, D. Kurath, D. J. Millener, and D. Strottman for valuable discussions and communication of results prior to publication.We report the observation of a laser-induced charge-transfer collision. In the presence of an intense laser beam, ground-state calcium ions collide with ground-state strontium atoms, selectively producing excited strontium ions and calcium neutrals. The laser-induced collision cross section has a linewidth of about 50 cm" 1 and peaks ~ 70 cm" 1 from that wavelength which satisfies the energy defect of the separated atoms.This Letter describes experimental observations which we believe demonstrate, for the first time, a laser-induced charge-transfer collision. 1 " 4 Energy is first stored in the form of ground-state ions of one species 0 An intense laser field is than used to transfer this energy rapidly and selectively to an excited ionic state of a second species.The process studied is Ca + (4s 2 S 1/2 ) + Sr(5s 21 S 0 )+^co ^Ca(4s 21 S 0 ) + Sr + *(5£ 2 P 3/2°)and is shown schematically in Fig. 1. Without the laser photon, Eq. (1) is endothermic by 2.6 eV (~ 30 kT at 1000°K) and has a vanishingly small cross section. The laser photon supplies this energy and may be thought of as raising one of the two Sr valence electrons to a virtual level of approximately Sr (5s5p 1 P 1°) character; the unexcited Sr electron can than be captured by Ca + , leaving Sr in the Sr + (5p 2 P 3/2°) excited state. Theory predicts 1 " 4 that, in contrast to the case of the previously studied dipole-dipole processes, 5 " 17 the maximum cross section for the laser-induced charge-transfer process should occur when the laser is tuned to a wavelength shifted (typically) by about 100 cm' 1 from that which exactly satis-120

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Re-examination of the spectrum of strontium: autoionization in the spectrum of neutral strontium

Cited by 32 publications

References 9 publications

Detection of the even parity,J=0–3, autoionizing 4dnl Rydberg states of strontium by two-step laser optogalvanic spectroscopy

Detection of the even parity,J=0–3, autoionizing 4dnl Rydberg states of strontium by two-step laser optogalvanic spectroscopy

EigenchannelR-matrix study of two-photon excitation of low-lying autoionizing states in strontium: dielectronic core-polarization effects

Laser-Induced Charge Transfer to an Excited Ionic State

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