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| 3. |
- Fredriksson, K, et al.
(författare)
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Investigation of the fine structure in the 2 D sequence of sodium using level-crossing spectroscopy
- 1976
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Ingår i: Journal of Physics B: Atomic and Molecular Physics. - : IOP Publishing. - 0022-3700. ; 9:8, s. 1237-1246
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Tidskriftsartikel (refereegranskat)abstract
- Splittings in the n 2 D sequence were measured for n=4-9. An accuracy of about 0.1% was obtained in level-crossing measurements on an atomic beam. The D states were populated by step-wise excitation, using an RF lamp and a CW dye laser. A method for measuring the sign of the spin-orbit coupling constant is demonstrated. With the present measurements, the highly anomalous n 2 D sequence in sodium has now been studied for n=3-16.
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| 4. |
- Grundevik, P, et al.
(författare)
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Hyperfine-structure study in the P sequence of 23 Na using quantum-beam spectroscopy
- 1979
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Ingår i: Journal of Physics B: Atomic and Molecular Physics. - : IOP Publishing. - 0022-3700. ; 12:16
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Tidskriftsartikel (refereegranskat)abstract
- Describes use of the quantum-beat method to study hyperfine structure in the 5 2 P 3/2 and 6 2 P 3/2 states of 23 Na. A pulsed dye laser, frequency-doubled into the UV region, was used to excite sodium atoms abruptly in a beam. The fluorescent light was recorded with a fast transient digitiser, interfaced to a micro-computer. Theoretical calculations using many-body perturbation theory were performed for the entire P sequence measured so far, taking polarisation and correlation effects into account separately. Very good agreement between experimental and theoretical values was obtained.
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| 5. |
- Hedin, Lars, et al.
(författare)
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Polarization corrections to core levels
- 1969
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Ingår i: Journal of Physics B: Atomic and Molecular Physics. - : IOP Publishing. - 0022-3700. ; 2:12
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical predictions for ionization energies of inner core electrons generally come out much more accurately by taking the difference between the total energies of two self-consistent Hartree-Fock calculations than by using Koopmans' theorem. For the outer core electrons, on the other hand, little or no improvement over Koopmans' theorem is obtained from a `ΔSCF method'. We show here that the difference between the results from the ΔSCF method and from Koopmans' theorem can be expressed in terms of a polarization potential. A simple physical argument can then be made as well as a comparison with second-order perturbation theory, which both show why the ΔSCF method should give good results for inner core levels but not necessarily for outer core levels. The formulation in terms of a polarization potential allows a systematic discussion and an easy calculation of chemical shifts in core levels. We find that the core electrons serve as probes on the charge density and the polarizability of the valence electron system. As numerical examples, results are given for ions, atoms and metals of sodium and potassium. The limitations and possible extensions of the theory are discussed.
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| 6. |
- Lundberg, Hans, et al.
(författare)
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Hyperfine structure in the sequence of sodium S states
- 1977
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Ingår i: Journal of Physics B: Atomic and Molecular Physics. - : IOP Publishing. - 0022-3700. ; 10:10, s. 1971-1978
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Tidskriftsartikel (refereegranskat)abstract
- The hyperfine structure for the 6, 7 and 8 2 S 1/2 states of 23 Na was measured by optical double-resonance techniques. The states were populated by step-wise excitation using two CW dye lasers. For the dipole interaction constant a, a(6 2 S 1/2 ) = 37.5(2) MHz, a(7 2 S 1/2 )=20.9(1) MHz, a(8 2 S 1/2 )=12.85(10) MHz. were obtained. Theoretical calculations of the hyperfine structure were performed for the 3-8 2 S 1/2 states using many-body perturbation techniques. When polarization as well as certain correlation effects are included in the calculation, an agreement with the experimental values within 2% is obtained.
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| 7. |
- Svanberg, Sune, et al.
(författare)
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Determination of hyperfine structure and g j factors in the sequences of 2 D states in alkali atoms using a tunable dye laser
- 1974
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Ingår i: Journal of Physics B: Atomic and Molecular Physics. - : IOP Publishing. - 0022-3700. ; 7:3
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Tidskriftsartikel (refereegranskat)abstract
- We have extended recently reported hyperfine structure studies of 2D states in alkali atoms to several new states. The 2D states were populated in a two-step excitation scheme, involving a conventional RF lamp and a cw tunable dye laser. Using level crossing and optical double resonance techniques we have determined the hyperfine structure of the 8 2D3/2,5/a states in 8TRb and the 11, 12, 13, 14 aD3/a,5/a states in 133Cs. Further, g, factors for several of these states were determined.
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| 8. |
- Jones, L A, et al.
(författare)
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Measurement of the total collisional ionization rates of Ne VI, VII and VIII
- 1977
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Ingår i: J Phys B. - : Institute of Physics (IOP). ; 10, s. 187-195
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Tidskriftsartikel (refereegranskat)abstract
- The total collisional ionization rates of neon VI, VII and VIII have been measured in a time-evolving theta-pinch plasma. The method used was to calculate the expected emission from the plasma using the measured time- and space-dependent electron density (1016-1017 cm-3) and temperature (120-400 eV). The semi-empirical ionization rates of Kunze and Lotz were used in the calculation and were adjusted, by multiplying with a constant, so that the predicted photon emission matched the observed line emission. The multiplicative factors, with estimated errors, required for best fit are: for neon VI, 0.15+or-0.1; for neon VII, 0.4+or-0.2; and for neon VIII, 0.7+or-0.25.
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