Abstract

Spectrograms of 208Pb electrodeless discharge tubes operated in a field of 24025 gauss gave Zeeman patterns for fifty-eight PbI spectral transitions from 2189 to 10969 Å and yielded eighteen new g values. There was good agreement between these and the g values predicted by intermediate-coupling eigenvectors determined from least-squares level fitting. The g value of the odd level at 58517 cm−1 indicates that it belongs to the 6p6d configuration instead of 6s6p3 as formerly classified.

A striking consequence of configuration interaction has been discovered which results in the total suppression of what would otherwise be a strong line in this spectrum. A predominantly 6p6d level is mixed with 6p7s and interference between the dipole matrix elements connecting respectively the 6d and 7s portions with a ground-state level causes a net dipole moment of almost exactly zero for this transition. However, even in our relatively weak magnetic field, this balance is upset by magnetic mixing of only 0.3% with a third level to enhance the line strength by at least a factor 106! Two related transitions with normal pattern separations display pronounced anomalies in the relative intensities of their Zeeman components. We give a theoretical analysis and quantitative calculations to show that these anomalies are due to combined interference effects of the two types of mixing.

© 1968 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. D. R. Wood and K. L. Andrew, J. Opt. Soc. Am. 58, 818 (1968).
    [Crossref]
  2. R. D. Cowan and K. L. Andrew, J. Opt. Soc. Am. 55, 502 (1965).
    [Crossref]
  3. K. L. Vander Sluis, J. Opt. Soc. Am. 46, 605 (1956).
    [Crossref]
  4. K. L. Andrew, R. D. Cowan, and A. Giacchetti, J. Opt. Soc. Am. 57, 715 (1967).
    [Crossref]
  5. W. R. S. Garton and M. Wilson, Troc. Phys. Soc. 87, 841 (1966).
    [Crossref]
  6. If the quantum-state compositions were 100% pure, the intensities of both lines would be exactly zero because of the selection rule Δj= 0 for the nonjumping electron. However, the least-squares energy-level fit indicates that the 6p2(32,32)2level is about 5% (32,12)2[or, equivalently, (12,32)2], so that both of the 4063 and 4062 Å lines could be expected to have appreciable intensities (and indeed, if the upper states were pure 12[32], then the 4063 line would be nine times stronger than the 4062 line).
  7. R. D. Cowan, Phys. Rev. 163, 54 (1967).
    [Crossref]

1968 (1)

1967 (2)

1966 (1)

W. R. S. Garton and M. Wilson, Troc. Phys. Soc. 87, 841 (1966).
[Crossref]

1965 (1)

1956 (1)

J. Opt. Soc. Am. (4)

Phys. Rev. (1)

R. D. Cowan, Phys. Rev. 163, 54 (1967).
[Crossref]

Troc. Phys. Soc. (1)

W. R. S. Garton and M. Wilson, Troc. Phys. Soc. 87, 841 (1966).
[Crossref]

Other (1)

If the quantum-state compositions were 100% pure, the intensities of both lines would be exactly zero because of the selection rule Δj= 0 for the nonjumping electron. However, the least-squares energy-level fit indicates that the 6p2(32,32)2level is about 5% (32,12)2[or, equivalently, (12,32)2], so that both of the 4063 and 4062 Å lines could be expected to have appreciable intensities (and indeed, if the upper states were pure 12[32], then the 4063 line would be nine times stronger than the 4062 line).

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 (7)

Fig. 1
Fig. 1

Zeeman pattern (π components above, σ components below) of the line 2613 Å, 6 p 2 ( 3 2 , 1 2 ) 1 6 p 6 d 1 2 [ 3 2 ] 1 photographed at 24 025 G. In an unperturbed pattern, the intensity of the central π component would be zero, and the intensities of the other two components would be equal, as would the intensities of all four σ components.

Fig. 2
Fig. 2

Zeeman pattern of the line 2822 Å, 6 p 2 ( 3 2 , 1 2 ) 2 6 p 6 d 1 2 [ 3 2 ] 1 photographed at 24 025 G. In an unperturbed pattern, the central π component would be strongest (instead of barely visible), and the σ components would be shaded in. (Incomplete optical separation of the two polarizations is responsible for the intermingling of the pi and sigma components within the same exposure.)

Fig. 3
Fig. 3

Zeeman pattern of the line 4063 Å, 6 p 2 ( 3 2 , 1 2 ) 2 6 p 6 d 1 2 [ 3 2 ] 2, appearing as an unresolved pseudo triplet at 24025 G. Note the complete absence of this line in the no-field exposure, even though 4062 Å has about the same intensity in the no-field exposure as it does in the 5 h π exposure. (Incomplete optical separation of the two polarizations is responsible for the intermingling of the pi and sigma components within the same exposure.)

Fig. 4
Fig. 4

Computed total line strengths of the three possible pairs of lines 6 p 2 6 p 6 d 1 2 [ 3 2 ] 1 , 2 as a function of the reduced dipole matrix element P6p,7s = (6pr∥7s). All curves are for a source in a magnetic field of 24 025 G, except for the two lowest ones. The experimental observations correspond to the case P6p,7s = 2.2a0, indicated by the vertical arrows. (Numbers in parentheses are estimated relative intensities for the zero-field case.)

Fig. 5
Fig. 5

Variation with P6p,7s of the computed Zeeman pattern of the 2822-Å line at 24025 G. Following the usual convention, π components have been plotted above, and σ components below, the horizontal lines. In order that all patterns could be plotted on the same vertical scale, values of the dipole matrix elements D rather than line strengths S = D2 have been plotted. Negative values of D are indicated by solid lines, positive values by dotted ones. In the limits P6p,7s → 0 or ∞, the computed pattern becomes approximately a normal 2–1 shaded-in pattern; the highly anomalous observed pattern is best approximated by the computed pattern for P6p,7s = 2.22a0.

Fig. 6
Fig. 6

Upper portion: The unperturbed Zeeman pattern of the 2822-Å line. Lower portion: The computed Zeeman pattern at 24025 G with interactions included, for P6p,7s = 2.22a0. The observed pattern is shown by microdensitometer tracings of a third-order spectrogram—the σ tracing being inverted, and the π and σ tracings separated vertically for clarity. The densitometer tracings are of course highly non-linear in intensity; strong σ lines can therefore be seen weakly in the π exposure, and vice versa. (Line strengths of the plotted unperturbed pattern must be divided by a factor of 10 to put them on the same vertical scale used in plotting the computed perturbed pattern.)

Fig. 7
Fig. 7

Similar to Fig. 5, except for the 2613-Å line. (Both computed patterns are plotted on the same vertical scale, and the microdensitometer tracings are of fourth-order exposures.)

Tables (2)

Tables Icon

Table I Experimental g factors, and g factors calculated for intermediate coupling from Slater-parameter fitting of the energy structure.

Tables Icon

Table II Energy parameters and dipole moments.

Equations (6)

Equations on this page are rendered with MathJax. Learn more.

D L S ( l 2 L S J M | P q ( 1 ) | l l L S J M ) = ( 1 ) J M ( J 1 J M q M ) ( l 2 L S J P ( 1 ) l l L S J ) = ( 1 ) J M ( J 1 J M q M ) δ S S ( 1 ) L + S + J + 1 ( [ J ] [ J ] ) 1 2 { J J 1 L L S } ( l 2 L P ( 1 ) l l L ) = ( 1 ) J M ( J 1 J M q M ) δ S S ( 1 ) l + l + S + J ( 2 [ L ] [ L ] [ J ] [ J ] ) 1 2 { L L 1 l l l } { J J 1 L L S } P u
= ( J 1 J M q M ) C L S l L J P u ,
| β J M ) = L S | l 2 L S J M ) B L S J β ,
| β M ) = l L S J | l l L S J M ) B l L S J M β ;
D β β = ( J 1 1 M q M ) L S B L S J β × l L C L S l L 1 P u B l L S 1 M β + ( J 1 2 M q M ) × L S B L S J β l L C L S l L 2 P u B l L S 2 M β ,
( J 1 2 M q M ) 2