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The Spectra of some Lithium-like and Sodium-like Atoms

Published online by Cambridge University Press:  24 October 2008

D. R. Hartree
Affiliation:
St John's College

Extract

It is possible to obtain approximate theoretical relations between the spectra of different atoms ionised to such an extent that they possess the same electron structure. In this paper these relations are used to extrapolate values of the terms of the spectra of various lithium-like and sodium-like atoms.

From the terms so estimated lines can be calculated, and in many cases correlated with lines observed by Millikan and Bowen in the hot spark spectrum of the corresponding element. Revised term values can then be calculated from the lines so identified.

The spectra of lithium-like atoms treated in this way include those from Be II up to O VI, and those of sodium-like atoms, the spectra P V and S VI.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1924

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References

* Millikan, R. A. and Bowen, I. C., Phys. Rev., vol. 22, p. 1 (1924)CrossRefGoogle Scholar.

In any atom, ionised or not, the most loosely bound electrons may be called the series electrons, and the spectrum arising from their transitions between various orbits will be called the optical spectrum even if it lies partly in the “X-ray” region. The rest of the atom or ion will be referred to as the core and the term X-ray spectra must be taken to mean spectra arising from transitions involving core orbits.

Millikan (loc. cit.), however, uses the term “hydrogen-like” for any atom “with one valence electron.”

* Note added in Proof. From Prof. Fowler's work on the spectra of silicon (Bakerian Lecture, 1924) the spectra of three Mg-like atoms are now known.

Fowler, A., Proc. Roy. Soc., vol. 103, p. 413 (1923); vol. 105, p. 299 (1924)CrossRefGoogle Scholar; Paschen, F., Ann. der Phys., vol. 71, pp. 142, 537 (1923)CrossRefGoogle Scholar.

* Bohr, N., Ann. der Phys., vol. 71, p. 263.Google Scholar

* Observed line very strong for this transition, probably not B III, but it may be obscuring the B III line.

Observed line stronger than would be expected for this transition.

Not tabulated by Millikan but mentioned in text as λλ = 2066·0, 2064·2, strongest lines on plate; and identified by him as first principal pair.

* Paschen-Götze, , Seriengesetze der Linienspektren, p. 71.Google Scholar

Millikan and Bowen, loc. cit.

* See addendum for more accurate term values based on later work of Millikan and Bowen.

* Paschen-Götze, loc. cit.

* Not observed by Millikan, given by Simeon.

Observed in spectrum of 30 volt arc.

Observed in spectrum of 40 volt arc.

§ Given by Millikan as probably Si. Doublet Δν = 84 according to Simeon.

Given by Simeon, as νν 64587, 64483 (Δν = 104).

* See Simeon, F., Proc. Roy. Soc., vol. 104, p. 368 (1923)CrossRefGoogle Scholar. Of the lines which are considered as probably due to C IV, Simeon (loc. cit. and Proc. Roy. Soc., vol. 102, p. 488 (1922)Google Scholar) only gives the first principal pair, and a line which may be the same as Millikan's line ν/R = 2·170, though the two observers' wave lengths differ a good deal more than for most other lines.

The strong line ν/R = 0·683 (λ = 1335·0) is suggested by Millikan for the first line of the principal series of C IV, but as it appears in the 30 volt arc this is unlikely. Also it does not fit in at all with the regular progression of the corresponding lines of the earlier elements (cf. § 3·6).

* Merton, , Proc. Roy. Soc., vol. 91, p. 498 (1915)CrossRefGoogle Scholar. A table of the chief unidentified Wolf-Rayet lines is given in this paper. One line and one pair observed by Merton are included in the spectrum C II given recently by Fowler, A., Proc. Roy. Soc., vol. 105, p. 299 (1924)CrossRefGoogle Scholar.

Fowler, A., Report on Series in Line Spectra, p. 164.Google Scholar

* There is just a possibility that the lines ν/R = 1·053, 1·046 form the first diffuse pair; the difference of intensity is rather large but it is in the right direction and the separation is about correct.

* Fowler, A., Proc. Roy. Soc., vol. 103, p. 426 (1923)CrossRefGoogle Scholar.