The spectra of Cs iii, Ba iv, and La v have been observed in a sliding spark discharge on the 10.7 m normal-incidence vacuum spectrograph at NBS. Analysis of the observations of Cs iii and La v has yielded the energy levels of the 5s25p5 and 5s5p6 configurations and nearly all levels of the 5s25p45d and 5s25p46s configurations that can combine with the 5s25p5 2P° ground term. The observations for Ba iv have yielded the levels of the 5s25p5 and 5s5p6 configurations. The 5s25p45d + 5s25p46s + 5s5p6 levels of Cs iii and La v have been theoretically interpreted, with configuration interaction included. The energy parameters determined from a least-squares fit to the observed level values are compared with Hartree-Fock calculations. The ionization energies are found to be 33.38 ± 0.25 eV for Cs iii, 47.1 ± 0.6 eV for Ba iv, and 61.6 ± 0.6 eV for La v. By extrapolating these values the ionization energy of Ce vi is estimated as 77.6 ± 1.2 eV.
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Classified lines of Cs iii. Intensities are visual estimates of photographic blackening: p = perturbed. The 5p45d levels are given in LS notation; the 5p46s levels are given in J1j notation. The uncertainty of the wavelengths is ± 0.005 Å.
Observed as a hyperfine doublet with a splitting of 2.45 ± 0.07 cm−1, weaker component on high wavelength side.
TABLE II
Energy levels for Cs iii and La v. Note that some of the levels of La v are slightly out of order, numerically. Where no uncertainty in the level value is listed, the uncertainty corresponds to a possible error in the wavelength of ±0.005 Å: at 120 000 cm−1, ±1.0 cm−1; at 200 000 cm−1, ±2.0 cm−1; at 245 000 cm−1, ±3.0 cm−1.
Calculated energy-level values in cm−1 and percentage compositions for the 5s5p6, 5s25p45d, and 5s25p46s configurations of Cs iii. The states of 5s25p46s are denoted by an asterisk. Negative eigenvector components are preceded by a minus sign.
Value of Eav for 5s25p5 set equal to one-half HF value of ζ5p.
Values in parentheses are the ratio of the calculated Rk to a value calculated by using the absolute value of each wave function.
Fixed at HF value.
Fixed at HF ratio to R2(5p6s, 5p5d).
TABLE V
Resonance lines of Ba iv. The uncertainty of the wavelengths is ± 0.005 Å.
λ (Å)
Int.
σ (cm−1)
Classification
794.888
40 000
125 803.9
5s25p5 2P3/2-5s5p6 2S1/2
923.743
50 000
108 255.2
5s25p5 2P1/2-5s5p6 2S1/2
TABLE VI
Energy levels of Ba iv.
Configuration
Term
J
E (cm−1)
5s25p5
2P°
0.0
2P°
17 548.7 ± 1.0
5s5p6
2S
125 803.9 ± 0.8
TABLE VII
Classified lines of La v. Intensities are visual estimates of photographic blackening. The 5p45d levels are given in LS notation; the 5p46s levels are given in J1j notation. The uncertainty of the wavelengths is ± 0.005 Å.
Observed as a hyperfine doublet with a splitting of 3.37 ± 0.05 cm−1, weaker component on high wavelength side.
Observed as a hyperfine doublet with a splitting of 5.50 ± 0.06 cm−1, weaker component on high wavelength side.
TABLE VIII
Calculated energy-level values in cm−1 and percentage compositions for the 5s5p6, 5s25p45d, and 5s25p46s configurations of La v. The states of 5s25p46s are denoted by an asterisk. Negative eigenvector components are preceded by a minus sign.
1 eV = 8065.479 cm−1; see E. R. Cohen and B. N. Taylor, “The 1973 Least-Squares Adjustment of the Fundamental Constants,” J. Phys. Chem. Ref. Data 2, 663–734 (1973).
Tables (10)
TABLE I
Classified lines of Cs iii. Intensities are visual estimates of photographic blackening: p = perturbed. The 5p45d levels are given in LS notation; the 5p46s levels are given in J1j notation. The uncertainty of the wavelengths is ± 0.005 Å.
Observed as a hyperfine doublet with a splitting of 2.45 ± 0.07 cm−1, weaker component on high wavelength side.
TABLE II
Energy levels for Cs iii and La v. Note that some of the levels of La v are slightly out of order, numerically. Where no uncertainty in the level value is listed, the uncertainty corresponds to a possible error in the wavelength of ±0.005 Å: at 120 000 cm−1, ±1.0 cm−1; at 200 000 cm−1, ±2.0 cm−1; at 245 000 cm−1, ±3.0 cm−1.
Calculated energy-level values in cm−1 and percentage compositions for the 5s5p6, 5s25p45d, and 5s25p46s configurations of Cs iii. The states of 5s25p46s are denoted by an asterisk. Negative eigenvector components are preceded by a minus sign.
Value of Eav for 5s25p5 set equal to one-half HF value of ζ5p.
Values in parentheses are the ratio of the calculated Rk to a value calculated by using the absolute value of each wave function.
Fixed at HF value.
Fixed at HF ratio to R2(5p6s, 5p5d).
TABLE V
Resonance lines of Ba iv. The uncertainty of the wavelengths is ± 0.005 Å.
λ (Å)
Int.
σ (cm−1)
Classification
794.888
40 000
125 803.9
5s25p5 2P3/2-5s5p6 2S1/2
923.743
50 000
108 255.2
5s25p5 2P1/2-5s5p6 2S1/2
TABLE VI
Energy levels of Ba iv.
Configuration
Term
J
E (cm−1)
5s25p5
2P°
0.0
2P°
17 548.7 ± 1.0
5s5p6
2S
125 803.9 ± 0.8
TABLE VII
Classified lines of La v. Intensities are visual estimates of photographic blackening. The 5p45d levels are given in LS notation; the 5p46s levels are given in J1j notation. The uncertainty of the wavelengths is ± 0.005 Å.
Observed as a hyperfine doublet with a splitting of 3.37 ± 0.05 cm−1, weaker component on high wavelength side.
Observed as a hyperfine doublet with a splitting of 5.50 ± 0.06 cm−1, weaker component on high wavelength side.
TABLE VIII
Calculated energy-level values in cm−1 and percentage compositions for the 5s5p6, 5s25p45d, and 5s25p46s configurations of La v. The states of 5s25p46s are denoted by an asterisk. Negative eigenvector components are preceded by a minus sign.
1 eV = 8065.479 cm−1; see E. R. Cohen and B. N. Taylor, “The 1973 Least-Squares Adjustment of the Fundamental Constants,” J. Phys. Chem. Ref. Data 2, 663–734 (1973).