Abstract

The isotope spectrum shift in the 6707.8A resonance line of lithium has been used for the assay of the isotopes Li 6 and Li 7. A hollow cathode source loaded with 4 mg of Li2SO4 is excited at 35 ma using purified helium at about 2- to 3-mm pressure as support gas. Characteristics, such as tube geometry, pressure, sample life, flow rate of gas, current, and anode-cathode spacing have been studied to give reproducible line intensity ratios. Precision of the method based on a 95 percent confidence interval is about 6 percent of the Li 6 content or, by difference, about 0.5 percent of the Li 7 content in natural material.

Spectra are obtained with a 21-foot, 30,000 lines per inch grating spectrograph using first order for which the Li 6–Li 7 isotope shift of 0.159A is readily separated. A multiplier phototube (1P28) set on the 4603A lithium line is used in an integrating circuit as an exposure meter.

© 1952 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. A. S. Russell and R. Rossi, Proc. Roy. Soc. (London) 87, 478 (1912).
    [CrossRef]
  2. L. Aronberg, Astrophys. J. 47, 96 (1918).
    [CrossRef]
  3. J. L. Rose and R. K. Stranathan, Phys. Rev. 49, 916 (1936).
    [CrossRef]
  4. See, for example, S. Tolansky, High Resolution Spectroscopy, (Methuen and Company, Ltd., London, England, 1947).
  5. P. Zeeman, Proc. Koninkl. Nederland Akad. Wetensch. Amsterdam 16, 155 (1913).
  6. J. C. McLennan and D. S. Ainslee, Trans. Roy. Soc. Can. 18, 137 (1924).
  7. I. B. Green, J. Opt. Soc. Am. and Rev. Sci. Instr. 11, 213 (1925).
    [CrossRef]
  8. H. Schüler and E. Würm, Naturwiss. 15, 971 (1927).
    [CrossRef]
  9. D. S. Hughes and C. Eckart, Phys. Rev. 36, 694 (1930).
    [CrossRef]
  10. D. S. Hughes, Phys. Rev. 38, 857 (1931).
    [CrossRef]
  11. R. Baldock and J. R. Patton, (1951).
  12. Ornstein, Vreeswijk, and Wolfsohn, Physica 1, 53 (1934).
    [CrossRef]
  13. Available from National Research Corporation, Cambridge 42, Massachusetts.
  14. Performed by J. W. Redmond and co-workers, Assay Laboratory, Y-12 Area, Oak Ridge, Tennessee.
  15. G. H. Dieke, “Progress Report on a Study of Standard Methods for Spectrographic Analysis,” (Johns Hopkins University, 1943).

1936 (1)

J. L. Rose and R. K. Stranathan, Phys. Rev. 49, 916 (1936).
[CrossRef]

1934 (1)

Ornstein, Vreeswijk, and Wolfsohn, Physica 1, 53 (1934).
[CrossRef]

1931 (1)

D. S. Hughes, Phys. Rev. 38, 857 (1931).
[CrossRef]

1930 (1)

D. S. Hughes and C. Eckart, Phys. Rev. 36, 694 (1930).
[CrossRef]

1927 (1)

H. Schüler and E. Würm, Naturwiss. 15, 971 (1927).
[CrossRef]

1925 (1)

I. B. Green, J. Opt. Soc. Am. and Rev. Sci. Instr. 11, 213 (1925).
[CrossRef]

1924 (1)

J. C. McLennan and D. S. Ainslee, Trans. Roy. Soc. Can. 18, 137 (1924).

1918 (1)

L. Aronberg, Astrophys. J. 47, 96 (1918).
[CrossRef]

1913 (1)

P. Zeeman, Proc. Koninkl. Nederland Akad. Wetensch. Amsterdam 16, 155 (1913).

1912 (1)

A. S. Russell and R. Rossi, Proc. Roy. Soc. (London) 87, 478 (1912).
[CrossRef]

Ainslee, D. S.

J. C. McLennan and D. S. Ainslee, Trans. Roy. Soc. Can. 18, 137 (1924).

Aronberg, L.

L. Aronberg, Astrophys. J. 47, 96 (1918).
[CrossRef]

Baldock, R.

R. Baldock and J. R. Patton, (1951).

Dieke, G. H.

G. H. Dieke, “Progress Report on a Study of Standard Methods for Spectrographic Analysis,” (Johns Hopkins University, 1943).

Eckart, C.

D. S. Hughes and C. Eckart, Phys. Rev. 36, 694 (1930).
[CrossRef]

Green, I. B.

I. B. Green, J. Opt. Soc. Am. and Rev. Sci. Instr. 11, 213 (1925).
[CrossRef]

Hughes, D. S.

D. S. Hughes, Phys. Rev. 38, 857 (1931).
[CrossRef]

D. S. Hughes and C. Eckart, Phys. Rev. 36, 694 (1930).
[CrossRef]

McLennan, J. C.

J. C. McLennan and D. S. Ainslee, Trans. Roy. Soc. Can. 18, 137 (1924).

Ornstein,

Ornstein, Vreeswijk, and Wolfsohn, Physica 1, 53 (1934).
[CrossRef]

Patton, J. R.

R. Baldock and J. R. Patton, (1951).

Redmond, J. W.

Performed by J. W. Redmond and co-workers, Assay Laboratory, Y-12 Area, Oak Ridge, Tennessee.

Rose, J. L.

J. L. Rose and R. K. Stranathan, Phys. Rev. 49, 916 (1936).
[CrossRef]

Rossi, R.

A. S. Russell and R. Rossi, Proc. Roy. Soc. (London) 87, 478 (1912).
[CrossRef]

Russell, A. S.

A. S. Russell and R. Rossi, Proc. Roy. Soc. (London) 87, 478 (1912).
[CrossRef]

Schüler, H.

H. Schüler and E. Würm, Naturwiss. 15, 971 (1927).
[CrossRef]

Stranathan, R. K.

J. L. Rose and R. K. Stranathan, Phys. Rev. 49, 916 (1936).
[CrossRef]

Tolansky, S.

See, for example, S. Tolansky, High Resolution Spectroscopy, (Methuen and Company, Ltd., London, England, 1947).

Vreeswijk,

Ornstein, Vreeswijk, and Wolfsohn, Physica 1, 53 (1934).
[CrossRef]

Wolfsohn,

Ornstein, Vreeswijk, and Wolfsohn, Physica 1, 53 (1934).
[CrossRef]

Würm, E.

H. Schüler and E. Würm, Naturwiss. 15, 971 (1927).
[CrossRef]

Zeeman, P.

P. Zeeman, Proc. Koninkl. Nederland Akad. Wetensch. Amsterdam 16, 155 (1913).

Astrophys. J. (1)

L. Aronberg, Astrophys. J. 47, 96 (1918).
[CrossRef]

J. Opt. Soc. Am. and Rev. Sci. Instr. (1)

I. B. Green, J. Opt. Soc. Am. and Rev. Sci. Instr. 11, 213 (1925).
[CrossRef]

Naturwiss. (1)

H. Schüler and E. Würm, Naturwiss. 15, 971 (1927).
[CrossRef]

Phys. Rev. (3)

D. S. Hughes and C. Eckart, Phys. Rev. 36, 694 (1930).
[CrossRef]

D. S. Hughes, Phys. Rev. 38, 857 (1931).
[CrossRef]

J. L. Rose and R. K. Stranathan, Phys. Rev. 49, 916 (1936).
[CrossRef]

Physica (1)

Ornstein, Vreeswijk, and Wolfsohn, Physica 1, 53 (1934).
[CrossRef]

Proc. Koninkl. Nederland Akad. Wetensch. Amsterdam (1)

P. Zeeman, Proc. Koninkl. Nederland Akad. Wetensch. Amsterdam 16, 155 (1913).

Proc. Roy. Soc. (London) (1)

A. S. Russell and R. Rossi, Proc. Roy. Soc. (London) 87, 478 (1912).
[CrossRef]

Trans. Roy. Soc. Can. (1)

J. C. McLennan and D. S. Ainslee, Trans. Roy. Soc. Can. 18, 137 (1924).

Other (5)

See, for example, S. Tolansky, High Resolution Spectroscopy, (Methuen and Company, Ltd., London, England, 1947).

R. Baldock and J. R. Patton, (1951).

Available from National Research Corporation, Cambridge 42, Massachusetts.

Performed by J. W. Redmond and co-workers, Assay Laboratory, Y-12 Area, Oak Ridge, Tennessee.

G. H. Dieke, “Progress Report on a Study of Standard Methods for Spectrographic Analysis,” (Johns Hopkins University, 1943).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (8)

Fig. 1
Fig. 1

Theoretical structure of lithium line S 2 1 2 - P 2 ° 1 2 , 1 1 2 at 6707A. Line separation is 0.158A.

Fig. 2
Fig. 2

Isotope shift in lithium resonance doublet at 6707A. Top spectrum: Li 6; middle spectrum: Li 6 and Li 7; bottom spectrum: Li 7.

Fig. 3
Fig. 3

A simplified schematic design of the hollow cathode source showing both the assembled and exploded unit.

Fig. 4
Fig. 4

Schematic diagram of the vacuum system used in the continuous purification and circulation of helium gas. To protect the mercury diffusion pump from sulfur fumes, the liquid nitrogen trap at the bottom was added to the system.

Fig. 5
Fig. 5

Replicate spectra of typical lithium spectro-isotopogram. Top portion of spectra sectored at ratio 10:1, thus giving iso-density lines for Li 7 (line at top left) and Li 6 (line at bottom right).

Fig. 6
Fig. 6

Effect of helium pressure on line intensity ratio. Optimum operating conditions for minimum dependence of the ratio on pressure as well as for high light intensity are obtained at 2-mm helium pressure.

Fig. 7
Fig. 7

Effect of sample size on the line intensity ratio Li 6/Li 7. error sensitivity at 4-mg sample size is only 1 percent per milligram.

Fig. 8
Fig. 8

Line intensity ratio as a function of source current (or equivalent exposure time). Self-absorption effects occurring at the higher tube currents are greater for the more abundant Li 7 isotope lines. Error sensitivity at 50 ma is one-fourth of 1 percent in the line intensity ratio for 1-ma current error.

Tables (1)

Tables Icon

Table I Precision of spectro-isotopic analysis for Li 7 at normal abundance level (92.8 percent) (all samples as Li2SO4).