Photoabsorption of the 4d electrons in barium
D L Ederer; T B Lucatorto; E B Saloman; R P Madden; J Sugar; D L Ederer; Nat. Bur. Stand., Washington, DC, USA; T B Lucatorto; Nat. Bur. Stand., Washington, DC, USA; E B Saloman; Nat. Bur. Stand., Washington, DC, USA; R P Madden; Nat. Bur. Stand., Washington, DC, USA; J Sugar; Nat. Bur. Stand., Washington, DC, USA
Журнал:
Journal of Physics B: Atomic and Molecular Physics
Дата:
1975-02-21
Аннотация:
The absorption spectrum of gaseous barium was obtained between 120 AA and 140 AA, the region of the N<sub>IV,V</sub> thresholds. The similarity to lanthanum of some of the features observed in barium suggests that the 4f orbital contracts and overlaps the 4d orbit. This contraction produces two terms, <sup>3</sup>P and <sup>3</sup>D, of the 4d<sup>9</sup>4f configuration below the 4d ionization limits, while the large electrostatic exchange interaction drives the <sup>1</sup>P term of this configuration some 10 eV above the limit. Furthermore, extensive mixing of the 4d<sup>9</sup>(6s<sup>2</sup>)6p configuration with 4d<sup>9</sup>(5d<sup>2</sup>)6p and 4d<sup>9</sup>(5d6s)6p produces many weak resonances in addition to the resonances associated with the 4d<sup>9</sup>4f configuration. A suggested classification of these features is given with the aid of known features of the La I spectrum. Finally, from the known X-ray splitting of the N<sub>IV,V</sub> threshold and the energy interval between the 6s<sup>2</sup>6p <sup>2</sup>P and 6s<sup>2</sup> <sup>1</sup>S levels in La I and La II, the ionization thresholds of the 4d electron were determined to be 814800 (1000) cm<sup>-1</sup> and 792500 (1000) cm<sup>-1</sup>.
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