Abstract

The californium spectrum emitted by electrodeless lamps has been observed from 2320 to 28 600 Å (43 070 to 3495 cm−1) and the wavelengths of more than 13,000 lines measured. Energy-level analyses have yielded 136 even and 265 odd levels of Cf i and 40 even plus 172 odd levels of Cf ii. The hyperfine width and the Landé g value are given for many levels. Twelve electron configurations have been identified for Cf i and four for Cf ii. Observations of the hyperfine structures of 249Cf and 251Cf have confirmed the nuclear spins of 9/2 and 1/2 derived from nuclear decay systematics. The sign of the nuclear dipole moment has been determined to be negative for both isotopes. The lowest levels of some configurations of the elements Th through Es have been plotted versus the number of f electrons for the neutral and the singly ionized species. A similar plot for three configurations of the neutral lanthanides and actinides gives a comparison of the electronic structures in these two series.

© 1995 Optical Society of America

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References

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  1. S. G. Thompson, K. Street, Jr., A. Ghiorso, and G. T. Seaborg, "The new element californium," Phys. Rev. 80, 790–796 (1950).
    [CrossRef]
  2. J. G. Conway, E. K. Hulet, and R. J. Morrow, "Emission spectrum of californium," J. Opt. Soc. Am. 52, 222 (1962).
    [CrossRef]
  3. E. F. Worden and J. G. Conway, "Ground states and normal electronic configurations of californium I and II," J. Opt. Soc. Am. 60, 1144–1145 (1970).
    [CrossRef]
  4. J. G. Conway, E. F. Worden, J. Blaise, and J. Vergès, "The infrared spectrum of californium," Spectrochim. Acta B 32, 97–99 (1977).
    [CrossRef]
  5. R. C. Weast and M. J. Astle, eds., Handbook of Chemistry and Physics, 61st and later eds. (CRC, Boca Raton, Fla., 1980), p. E231; J. Reader, C. H. Corliss, W. L. Weise, and G. A. Martin, Wavelengths and Transition Probabilities for Atoms and Atomic Ions, Natl. Stand. Ref. Data Ser. Natl. Bur. Stand. 68 (1980).
  6. J. Blaise, J. Vergès, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Preliminary term analyses of neutral californium (Cf I) and singly ionized californium (Cf II)," presented at the 10th Conference of the European Group of Atomic Spectroscopy, Munich, July 11–14, 1978.
  7. J. Blaise, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Generalized parametric study of the 5ƒn and 5ƒns configurations," Phys. Scr. 22, 224–230 (1980).
    [CrossRef]
  8. J. Blaise and J.-F. Wyart, "U II," in Energy Levels and Atomic Spectra of the Actinides, Vol. 20 of Tables Internationales de Constantes Seléctionées (Université P. et Marie Curie, Paris, 1992).
  9. F. S. Tomkins and M. Fred, "Electrodeless discharge tubes containing rare earth and heavy element halides," J. Opt. Soc. Am. 47, 1087–1091 (1957).
    [CrossRef]
  10. E. F. Worden, R. G. Gutmacher, and J. G. Conway, "Use of electrodeless lamps in the analysis of atomic spectra," Appl. Opt. 2, 1087–1091 (1963).
    [CrossRef]
  11. F. S. Tomkins and M. Fred, "Wavelength measurements with a concave grating spectrograph," Appl. Opt. 2, 715–725 (1963); "The Argonne thirty-foot spectrograph," Spectrochim. Acta 6, 139–143 (1954).
    [CrossRef]
  12. F. P. J. Valero, "Thorium lamps and interferometrically measured thorium wavelengths," J. Opt. Soc. Am. 58, 484–489 (1968); A. Giacchetti, R. W. Stanley, and R. Zalubas, "Proposed secondary-standard wavelengths in the spectrum of thorium," J. Opt. Soc. Am. 60, 474–489 (1970).
    [CrossRef]
  13. E. F. Worden and J. G. Conway, "Energy levels of the first spectrum of curium, Cm I," J. Opt. Soc. Am. 66, 109–121 (1976); E. F. Worden, E. K. Hulet, R. G. Gutmacher, and J. G. Conway, "The emission spectrum of curium," At. Data Nucl. Data Tables 18, 459–495 (1976).
    [CrossRef]
  14. J. Blaise, J. G. Conway, and E. F. Worden, "Revisions and additions to the energy levels of neutral curium (244Cm I)," J. Opt. Soc. Am. B 5, 2093–2105 (1988).
    [CrossRef]
  15. C. M. Lederer and V. S. Shirley, eds., Table of Isotopes, 7th ed. (Wiley, New York, 1978).
  16. N. Edelstein and D. G. Karraker, "The EPR of Cf3+ in octahedral symmetry and the nuclear dipole moment of 249Cf," J. Chem. Phys. 62, 938–940 (1975).
    [CrossRef]
  17. C. H. Townes and A. L. Schalow, Microwave Spectroscopy (Dover, New York, 1975), pp. 512–514.
  18. H. Kopfermann, Nuclear Moments (Academic, New York, 1958), pp. 15, 17, 99, and 444.
  19. J. G. Conway and E. F. Worden, "Preliminary level analysis of the first and second spectra of dysprosium, Dy I and Dy II," J. Opt. Soc. Am. 61, 704–726 (1971).
    [CrossRef]
  20. W. C. Martin, R. Zalubas, and L. Hagan, Atomic Energy Levels— The Rare-Earth Elements, Natl. Stand. Ref. Data Ser. Natl. Bur. Stand. 60 (1978); J.-F. Wyart, "Interpretation nouvelle des raies de Dy I et Dy II," Ph.D. dissertation (Université Paris-Sud, Orsay, France, 1973).
  21. J. M. Blank, "Zeeman effect data and classification of the first spark spectrum of dysprosium," Ph.D. dissertation (Massachusetts Institute of Technology, Cambridge, Mass., 1952).
  22. J. W. Brault, "Rapid-scan high-resolution Fourier spectrometer for the visible," J. Opt. Soc. Am. 66, 1081 (A) (1976).
  23. C. Bauche-Arnoult, S. Gersternkorn, J. Vergés, and F. S. Tomkins, "Extended experimental and theoretical analysis of the hyperfine structure in the ground multiplets of Pu I and Pu II," J. Opt. Soc. Am. 63, 1199–1203 (1973).
    [CrossRef]
  24. L. Brewer, "Energies of the electronic configurations of the lanthanide and actinide neutral atoms," J. Opt. Soc. Am. 61, 1101–1111 (1971).
    [CrossRef]
  25. L. Brewer, "Energies of the electronic configurations of the singly, doubly, and triply ionized lanthanides and actinides," J. Opt. Soc. Am. 62, 1666–1682 (1972).
  26. M. Fred and F. S. Tomkins, "Preliminary analyses of Am I and Am II spectra," J. Opt. Soc. Am. 47, 1076–1087 (1957).
    [CrossRef]
  27. M. Fred, "Electronic structure of the actinide elements," in Lanthanide/Actinide Chemistry, P. R. Fields and T. Moeller, eds. (American Chemical Society, Washington, D.C., 1967), pp. 180–202.
    [CrossRef]

1988 (1)

1980 (1)

J. Blaise, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Generalized parametric study of the 5ƒn and 5ƒns configurations," Phys. Scr. 22, 224–230 (1980).
[CrossRef]

1977 (1)

J. G. Conway, E. F. Worden, J. Blaise, and J. Vergès, "The infrared spectrum of californium," Spectrochim. Acta B 32, 97–99 (1977).
[CrossRef]

1976 (2)

1975 (1)

N. Edelstein and D. G. Karraker, "The EPR of Cf3+ in octahedral symmetry and the nuclear dipole moment of 249Cf," J. Chem. Phys. 62, 938–940 (1975).
[CrossRef]

1973 (1)

1972 (1)

L. Brewer, "Energies of the electronic configurations of the singly, doubly, and triply ionized lanthanides and actinides," J. Opt. Soc. Am. 62, 1666–1682 (1972).

1971 (2)

1970 (1)

1968 (1)

1963 (2)

1962 (1)

1957 (2)

1950 (1)

S. G. Thompson, K. Street, Jr., A. Ghiorso, and G. T. Seaborg, "The new element californium," Phys. Rev. 80, 790–796 (1950).
[CrossRef]

Bauche-Arnoult, C.

Blaise, J.

J. Blaise, J. G. Conway, and E. F. Worden, "Revisions and additions to the energy levels of neutral curium (244Cm I)," J. Opt. Soc. Am. B 5, 2093–2105 (1988).
[CrossRef]

J. Blaise, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Generalized parametric study of the 5ƒn and 5ƒns configurations," Phys. Scr. 22, 224–230 (1980).
[CrossRef]

J. G. Conway, E. F. Worden, J. Blaise, and J. Vergès, "The infrared spectrum of californium," Spectrochim. Acta B 32, 97–99 (1977).
[CrossRef]

J. Blaise, J. Vergès, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Preliminary term analyses of neutral californium (Cf I) and singly ionized californium (Cf II)," presented at the 10th Conference of the European Group of Atomic Spectroscopy, Munich, July 11–14, 1978.

J. Blaise and J.-F. Wyart, "U II," in Energy Levels and Atomic Spectra of the Actinides, Vol. 20 of Tables Internationales de Constantes Seléctionées (Université P. et Marie Curie, Paris, 1992).

Blank, J. M.

J. M. Blank, "Zeeman effect data and classification of the first spark spectrum of dysprosium," Ph.D. dissertation (Massachusetts Institute of Technology, Cambridge, Mass., 1952).

Brault, J. W.

J. W. Brault, "Rapid-scan high-resolution Fourier spectrometer for the visible," J. Opt. Soc. Am. 66, 1081 (A) (1976).

Brewer, L.

L. Brewer, "Energies of the electronic configurations of the singly, doubly, and triply ionized lanthanides and actinides," J. Opt. Soc. Am. 62, 1666–1682 (1972).

L. Brewer, "Energies of the electronic configurations of the lanthanide and actinide neutral atoms," J. Opt. Soc. Am. 61, 1101–1111 (1971).
[CrossRef]

Conway, J. G.

J. Blaise, J. G. Conway, and E. F. Worden, "Revisions and additions to the energy levels of neutral curium (244Cm I)," J. Opt. Soc. Am. B 5, 2093–2105 (1988).
[CrossRef]

J. Blaise, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Generalized parametric study of the 5ƒn and 5ƒns configurations," Phys. Scr. 22, 224–230 (1980).
[CrossRef]

J. G. Conway, E. F. Worden, J. Blaise, and J. Vergès, "The infrared spectrum of californium," Spectrochim. Acta B 32, 97–99 (1977).
[CrossRef]

E. F. Worden and J. G. Conway, "Energy levels of the first spectrum of curium, Cm I," J. Opt. Soc. Am. 66, 109–121 (1976); E. F. Worden, E. K. Hulet, R. G. Gutmacher, and J. G. Conway, "The emission spectrum of curium," At. Data Nucl. Data Tables 18, 459–495 (1976).
[CrossRef]

J. G. Conway and E. F. Worden, "Preliminary level analysis of the first and second spectra of dysprosium, Dy I and Dy II," J. Opt. Soc. Am. 61, 704–726 (1971).
[CrossRef]

E. F. Worden and J. G. Conway, "Ground states and normal electronic configurations of californium I and II," J. Opt. Soc. Am. 60, 1144–1145 (1970).
[CrossRef]

E. F. Worden, R. G. Gutmacher, and J. G. Conway, "Use of electrodeless lamps in the analysis of atomic spectra," Appl. Opt. 2, 1087–1091 (1963).
[CrossRef]

J. G. Conway, E. K. Hulet, and R. J. Morrow, "Emission spectrum of californium," J. Opt. Soc. Am. 52, 222 (1962).
[CrossRef]

J. Blaise, J. Vergès, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Preliminary term analyses of neutral californium (Cf I) and singly ionized californium (Cf II)," presented at the 10th Conference of the European Group of Atomic Spectroscopy, Munich, July 11–14, 1978.

Edelstein, N.

N. Edelstein and D. G. Karraker, "The EPR of Cf3+ in octahedral symmetry and the nuclear dipole moment of 249Cf," J. Chem. Phys. 62, 938–940 (1975).
[CrossRef]

Fred, M.

Gersternkorn, S.

Ghiorso, A.

S. G. Thompson, K. Street, Jr., A. Ghiorso, and G. T. Seaborg, "The new element californium," Phys. Rev. 80, 790–796 (1950).
[CrossRef]

Gutmacher, R. G.

E. F. Worden, R. G. Gutmacher, and J. G. Conway, "Use of electrodeless lamps in the analysis of atomic spectra," Appl. Opt. 2, 1087–1091 (1963).
[CrossRef]

Hagan, L.

W. C. Martin, R. Zalubas, and L. Hagan, Atomic Energy Levels— The Rare-Earth Elements, Natl. Stand. Ref. Data Ser. Natl. Bur. Stand. 60 (1978); J.-F. Wyart, "Interpretation nouvelle des raies de Dy I et Dy II," Ph.D. dissertation (Université Paris-Sud, Orsay, France, 1973).

Hulet, E. K.

Karraker, D. G.

N. Edelstein and D. G. Karraker, "The EPR of Cf3+ in octahedral symmetry and the nuclear dipole moment of 249Cf," J. Chem. Phys. 62, 938–940 (1975).
[CrossRef]

Kopfermann, H.

H. Kopfermann, Nuclear Moments (Academic, New York, 1958), pp. 15, 17, 99, and 444.

Martin, W. C.

W. C. Martin, R. Zalubas, and L. Hagan, Atomic Energy Levels— The Rare-Earth Elements, Natl. Stand. Ref. Data Ser. Natl. Bur. Stand. 60 (1978); J.-F. Wyart, "Interpretation nouvelle des raies de Dy I et Dy II," Ph.D. dissertation (Université Paris-Sud, Orsay, France, 1973).

Morrow, R. J.

Schalow, A. L.

C. H. Townes and A. L. Schalow, Microwave Spectroscopy (Dover, New York, 1975), pp. 512–514.

Seaborg, G. T.

S. G. Thompson, K. Street, Jr., A. Ghiorso, and G. T. Seaborg, "The new element californium," Phys. Rev. 80, 790–796 (1950).
[CrossRef]

Street, K.

S. G. Thompson, K. Street, Jr., A. Ghiorso, and G. T. Seaborg, "The new element californium," Phys. Rev. 80, 790–796 (1950).
[CrossRef]

Thompson, S. G.

S. G. Thompson, K. Street, Jr., A. Ghiorso, and G. T. Seaborg, "The new element californium," Phys. Rev. 80, 790–796 (1950).
[CrossRef]

Tomkins, F. S.

Townes, C. H.

C. H. Townes and A. L. Schalow, Microwave Spectroscopy (Dover, New York, 1975), pp. 512–514.

Valero, F. P. J.

Vergés, J.

Vergès, J.

J. G. Conway, E. F. Worden, J. Blaise, and J. Vergès, "The infrared spectrum of californium," Spectrochim. Acta B 32, 97–99 (1977).
[CrossRef]

J. Blaise, J. Vergès, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Preliminary term analyses of neutral californium (Cf I) and singly ionized californium (Cf II)," presented at the 10th Conference of the European Group of Atomic Spectroscopy, Munich, July 11–14, 1978.

Worden, E. F.

J. Blaise, J. G. Conway, and E. F. Worden, "Revisions and additions to the energy levels of neutral curium (244Cm I)," J. Opt. Soc. Am. B 5, 2093–2105 (1988).
[CrossRef]

J. Blaise, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Generalized parametric study of the 5ƒn and 5ƒns configurations," Phys. Scr. 22, 224–230 (1980).
[CrossRef]

J. G. Conway, E. F. Worden, J. Blaise, and J. Vergès, "The infrared spectrum of californium," Spectrochim. Acta B 32, 97–99 (1977).
[CrossRef]

E. F. Worden and J. G. Conway, "Energy levels of the first spectrum of curium, Cm I," J. Opt. Soc. Am. 66, 109–121 (1976); E. F. Worden, E. K. Hulet, R. G. Gutmacher, and J. G. Conway, "The emission spectrum of curium," At. Data Nucl. Data Tables 18, 459–495 (1976).
[CrossRef]

J. G. Conway and E. F. Worden, "Preliminary level analysis of the first and second spectra of dysprosium, Dy I and Dy II," J. Opt. Soc. Am. 61, 704–726 (1971).
[CrossRef]

E. F. Worden and J. G. Conway, "Ground states and normal electronic configurations of californium I and II," J. Opt. Soc. Am. 60, 1144–1145 (1970).
[CrossRef]

E. F. Worden, R. G. Gutmacher, and J. G. Conway, "Use of electrodeless lamps in the analysis of atomic spectra," Appl. Opt. 2, 1087–1091 (1963).
[CrossRef]

J. Blaise, J. Vergès, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Preliminary term analyses of neutral californium (Cf I) and singly ionized californium (Cf II)," presented at the 10th Conference of the European Group of Atomic Spectroscopy, Munich, July 11–14, 1978.

Wyart, J.-F.

J. Blaise, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Generalized parametric study of the 5ƒn and 5ƒns configurations," Phys. Scr. 22, 224–230 (1980).
[CrossRef]

J. Blaise and J.-F. Wyart, "U II," in Energy Levels and Atomic Spectra of the Actinides, Vol. 20 of Tables Internationales de Constantes Seléctionées (Université P. et Marie Curie, Paris, 1992).

J. Blaise, J. Vergès, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Preliminary term analyses of neutral californium (Cf I) and singly ionized californium (Cf II)," presented at the 10th Conference of the European Group of Atomic Spectroscopy, Munich, July 11–14, 1978.

Zalubas, R.

W. C. Martin, R. Zalubas, and L. Hagan, Atomic Energy Levels— The Rare-Earth Elements, Natl. Stand. Ref. Data Ser. Natl. Bur. Stand. 60 (1978); J.-F. Wyart, "Interpretation nouvelle des raies de Dy I et Dy II," Ph.D. dissertation (Université Paris-Sud, Orsay, France, 1973).

Appl. Opt. (2)

J. Chem. Phys. (1)

N. Edelstein and D. G. Karraker, "The EPR of Cf3+ in octahedral symmetry and the nuclear dipole moment of 249Cf," J. Chem. Phys. 62, 938–940 (1975).
[CrossRef]

J. Opt. Soc. Am. (11)

J. G. Conway and E. F. Worden, "Preliminary level analysis of the first and second spectra of dysprosium, Dy I and Dy II," J. Opt. Soc. Am. 61, 704–726 (1971).
[CrossRef]

F. P. J. Valero, "Thorium lamps and interferometrically measured thorium wavelengths," J. Opt. Soc. Am. 58, 484–489 (1968); A. Giacchetti, R. W. Stanley, and R. Zalubas, "Proposed secondary-standard wavelengths in the spectrum of thorium," J. Opt. Soc. Am. 60, 474–489 (1970).
[CrossRef]

E. F. Worden and J. G. Conway, "Energy levels of the first spectrum of curium, Cm I," J. Opt. Soc. Am. 66, 109–121 (1976); E. F. Worden, E. K. Hulet, R. G. Gutmacher, and J. G. Conway, "The emission spectrum of curium," At. Data Nucl. Data Tables 18, 459–495 (1976).
[CrossRef]

J. G. Conway, E. K. Hulet, and R. J. Morrow, "Emission spectrum of californium," J. Opt. Soc. Am. 52, 222 (1962).
[CrossRef]

E. F. Worden and J. G. Conway, "Ground states and normal electronic configurations of californium I and II," J. Opt. Soc. Am. 60, 1144–1145 (1970).
[CrossRef]

F. S. Tomkins and M. Fred, "Electrodeless discharge tubes containing rare earth and heavy element halides," J. Opt. Soc. Am. 47, 1087–1091 (1957).
[CrossRef]

J. W. Brault, "Rapid-scan high-resolution Fourier spectrometer for the visible," J. Opt. Soc. Am. 66, 1081 (A) (1976).

C. Bauche-Arnoult, S. Gersternkorn, J. Vergés, and F. S. Tomkins, "Extended experimental and theoretical analysis of the hyperfine structure in the ground multiplets of Pu I and Pu II," J. Opt. Soc. Am. 63, 1199–1203 (1973).
[CrossRef]

L. Brewer, "Energies of the electronic configurations of the lanthanide and actinide neutral atoms," J. Opt. Soc. Am. 61, 1101–1111 (1971).
[CrossRef]

L. Brewer, "Energies of the electronic configurations of the singly, doubly, and triply ionized lanthanides and actinides," J. Opt. Soc. Am. 62, 1666–1682 (1972).

M. Fred and F. S. Tomkins, "Preliminary analyses of Am I and Am II spectra," J. Opt. Soc. Am. 47, 1076–1087 (1957).
[CrossRef]

J. Opt. Soc. Am. B (1)

Phys. Rev. (1)

S. G. Thompson, K. Street, Jr., A. Ghiorso, and G. T. Seaborg, "The new element californium," Phys. Rev. 80, 790–796 (1950).
[CrossRef]

Phys. Scr. (1)

J. Blaise, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Generalized parametric study of the 5ƒn and 5ƒns configurations," Phys. Scr. 22, 224–230 (1980).
[CrossRef]

Spectrochim. Acta B (1)

J. G. Conway, E. F. Worden, J. Blaise, and J. Vergès, "The infrared spectrum of californium," Spectrochim. Acta B 32, 97–99 (1977).
[CrossRef]

Other (9)

R. C. Weast and M. J. Astle, eds., Handbook of Chemistry and Physics, 61st and later eds. (CRC, Boca Raton, Fla., 1980), p. E231; J. Reader, C. H. Corliss, W. L. Weise, and G. A. Martin, Wavelengths and Transition Probabilities for Atoms and Atomic Ions, Natl. Stand. Ref. Data Ser. Natl. Bur. Stand. 68 (1980).

J. Blaise, J. Vergès, J.-F. Wyart, J. G. Conway, and E. F. Worden, "Preliminary term analyses of neutral californium (Cf I) and singly ionized californium (Cf II)," presented at the 10th Conference of the European Group of Atomic Spectroscopy, Munich, July 11–14, 1978.

J. Blaise and J.-F. Wyart, "U II," in Energy Levels and Atomic Spectra of the Actinides, Vol. 20 of Tables Internationales de Constantes Seléctionées (Université P. et Marie Curie, Paris, 1992).

C. M. Lederer and V. S. Shirley, eds., Table of Isotopes, 7th ed. (Wiley, New York, 1978).

W. C. Martin, R. Zalubas, and L. Hagan, Atomic Energy Levels— The Rare-Earth Elements, Natl. Stand. Ref. Data Ser. Natl. Bur. Stand. 60 (1978); J.-F. Wyart, "Interpretation nouvelle des raies de Dy I et Dy II," Ph.D. dissertation (Université Paris-Sud, Orsay, France, 1973).

J. M. Blank, "Zeeman effect data and classification of the first spark spectrum of dysprosium," Ph.D. dissertation (Massachusetts Institute of Technology, Cambridge, Mass., 1952).

C. H. Townes and A. L. Schalow, Microwave Spectroscopy (Dover, New York, 1975), pp. 512–514.

H. Kopfermann, Nuclear Moments (Academic, New York, 1958), pp. 15, 17, 99, and 444.

M. Fred, "Electronic structure of the actinide elements," in Lanthanide/Actinide Chemistry, P. R. Fields and T. Moeller, eds. (American Chemical Society, Washington, D.C., 1967), pp. 180–202.
[CrossRef]

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Figures (14)

Fig. 1
Fig. 1

8.7-Å region (3664–3655 Å) of the 249Cf spectrum taken on the 9.15-m ANL spectrograph. The lamp type and the exposure times are listed to the right of the spectrum. The interferometric lines of the Th spectrum in adjacent spectra were used as wavelength standards. The 249Bk spectrum at the bottom was used to identify the lines of that element in the Cf spectrum. The strong Cf line under the arrow on the left-hand side of the figure is self-reversed. It is a transition from the ground state of Cf i, with a wavelength of 3662.67 Å.

Fig. 2
Fig. 2

249Cf spectrum line shapes caused by the 9/2 spin, the small nuclear magnetic moment, and limited instrument resolution: (a) for narrow component width; (b) for the same parameters, except the component width is near Doppler width. It is evident that the direction of degradation can be mistaken for lines with shapes like that in (b). (c) With parameters to give partial resolution. Shapes in (b) and (c) are representative of the shapes obtained under our experimental conditions. Letters with arrows show positions measured on lines with these shapes. The line width is from positions w, the line center from c, and the maximum from m (see text). (d) Observed infrared line at 5610 cm−1 with five resolved diagonal components and many unresolved components in the tail of the line. In (a) the simulated transition is for J = 7 to J = 6, with A7 ~ 0.033 cm−1 and A6 ~ 0.02 cm−1 and with B’s being roughly 0.01 and 0.008 cm−1. An off-diagonal component is under diagonal component 3, and the FF + 1 components are too weak to show.

Fig. 3
Fig. 3

Zeeman effect of the 5912-Å 249Cf line at 2.4 T observed with the 9.15-m ANL spectrograph. The pattern tells us that the transition is from a level with J = 8 to a level with J = 8. The measured Landé g values are 1.301 and 1.215 Lorentz units, respectively. The transition is from the 16 909.560-cm−1 level to the ground level of Cf i.

Fig. 4
Fig. 4

Zeeman effect of the 4099-Å line of 249Cf at 2.4 T showing an unresolved pattern of a transition where J2 = J1 + 1 and g1 > g2, the type-1 pattern shown in Fig. 5. The transition is from the J = 7 level of Cf i at 24 388.60 cm−1 to the J = 8 ground state. The no-field line is self-reversed. Such unresolved patterns can be measured to give g values by use of the formulas given in Fig. 5 when the J values of the levels are known.

Fig. 5
Fig. 5

Types of Zeeman patterns and formulas for determination of g values from unresolved patterns of transitions when the J values of the levels are known. The type of pattern for a line can be useful in determining the J value of levels with unknown J or in confirming an assignment.

Fig. 6
Fig. 6

Short region of the Cf spectrum from 5925 to 5901 Å, showing spectrum assignment. Lines of the neutral atom (Cf i) are identified by short vertical lines on the line below the spectra, and lines of the singly ionized atom (Cf ii) are identified by short vertical lines on the line above the spectra. As can be seen, spectra from the EDL at low density (low power) favor the ion lines and spectra from the EDL at high atom density (high input power) favor the neutral lines. To obtain these spectra, the emission intensity times the exposure time of the EDL was kept approximately constant. Spectrum assignment by this technique is not 100% accurate (see Refs. 10 and 13).

Fig. 7
Fig. 7

Small region of the Cf spectrum from 3664 to 3655 Å photographed on the ANL spectrograph with the lamp types indicated to the right of the spectra. The spectra with high250Cf content (87%) show the advantage of an even–even isotope with no hfs by exhibiting narrower lines, in most cases, than the adjacent 249Cf spectrum. The 250Cf spectrum is complicated slightly by the presence of roughly 6% each of 249Cf and 251Cf. The dots indicate the very strong and self-reversed 3662.7-Å line on the left and the 3655.6-Å line on the right.

Fig. 8
Fig. 8

Isotope shift of the 4335-Å, 23 060.38–0.00-cm−1 line of Cf photographed with all three lamp types. The configurations of the levels are 5f96d7s2 and 5f107s2. Because both configurations have paired s electrons, the hfs of the levels is small, and the 249Cf and the 251Cf lines are sharp. The isotope shift results because a nonshielding 6d electron is coverted to a shielding 5f electron in the transition. In the figure the frequency increases to the right, so the isotope shift of the upper level is positive relative to the ground state.

Fig. 9
Fig. 9

Profile of the 4902.215-cm−1 line of 249Cf, showing ten resolved diagonal components, as observed with the LAC FTS. The transition is from the J = 8 even level at 22 361 cm−1 to the J = 8 odd level of Cf i at 17 459 cm−1. Because the transition involves high J levels, the off-diagonal transitions are weak (and unresolved here). The number of strong diagonal components is I limited here (J > I) and is equal to 2I + 1. This result confirms that the nuclear spin of 249Cf is 9/2, as was derived previously by nuclear decay systematics.15

Fig. 10
Fig. 10

The 4088- Å, J = 13/2, 36 481-cm−1 to J = 11/2, 12 029-cm−1 transition of Cf ii on the left and the 3631- Å, J = 3/2, 38 646-cm−1 to J = 5/2, 11 114 cm−1 transition of Cf ii on the right each show a flag pattern for 249Cf and two diagonal components for 251Cf. The 251Cf-line off-diagonal components for transitions with J ≥ 3/2 (nearly all Cf lines) are very weak and are not visible. Numerous other lines exhibit this pattern, confirming that the spin of 251Cf is 1/2. The flag patterns degrade in the same direction for the same transition in both isotopes. Thus the sign of the nuclear magnetic dipole moment is the same for these two isotopes. The 252Cf line shows in the bottom exposure of the 4088-Å line just to the right of the 250Cf line. In the figure the frequency increases to the right.

Fig. 11
Fig. 11

Low-lying energy-level structure of the 5f107s2 and 5f107s configurations of Cf i and Cf ii. As can be seen from the figure, the knowledge of the level positions in one spectrum can help in the search for levels in the other spectrum.

Fig. 12
Fig. 12

Plot of the energy of the lowest levels of several configurations relative to the lowest level of the 5fN7s2 configuration as zero in the neutral elements Pa through Es. Note how the 5fN7s2 configuration becomes more stable as the series is ascended.

Fig. 13
Fig. 13

Plot of the lowest energy level for several configurations relative to the lowest energy level of the 5fN7s configuration as zero versus N for the singly ionized actinides Th through Es.

Fig. 14
Fig. 14

Positions of the energy of the lowest levels of the configurations fN−1dsp, fN−1ds2, and fNs2 for the actinides (gray) and the lanthanides (black) plotted versus N, with the lowest level of the fN−1ds2 configuration being at zero. The dashed level positions with dashed connector lines are predicted values from Brewer.25 For the lanthanides Pm, Sm, and Eu, the 4fN6s2 lowest levels were determined experimentally, but not for the 4fN−15d6s6p configuration or for 4fN−15d6s2 in Pm and Eu. In the actinides the lowest level for the 5fN−16d7s2 configuration in Es and for the 5fN−16d7s7p configuration in both Cf and Es is not shown. The lower energy of the actinide 5fN7s2 configuration after the half-filled shell is obvious. This result supports the lanthanide character of the middle actinide elements and the tendency for stable divalent character of the heavier actinides.

Tables (6)

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Table 1 Isotopic Composition of EDL’s Used to Observe the Cf Spectra

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Table 2 Even Energy Levels of Neutral Californium (249Cf i)

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Table 3 Odd Energy Levels of Neutral Californium (249Cf i)

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Table 4 Even Energy Levels of Singly Ionized Californium (249Cf ii)

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Table 5 Odd Energy Levels of Singly Ionized Californium (249Cf ii)

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Table 6 Lowest Levels of Known Configurations of Californium (249Cf)

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