Stripped Atoms of the First Long Period

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598

PHYSICS: GIBBS AND WHITE

PROC. N. A. S.-

gives a perfect "Glaser effect." Since both Glaser and I use the same method, viz., measure the moment of force exerted on a test body in an inhomogeneous magnetic field, the main sources of error should be the same for both. After several runs with H2, which gave constant specific susceptibility, I left the apparatus for a few days, and on returning obtained a good "Glaser effect," see curve I. Two more runs gave similar results. On examination of the cleaning train, which furnishes dry gas for my apparatus, the P205 in the last drying tube was found to have acquired a slight glaze, indicating presence of moisture. After dry P205 had been substituted for that previously used, curve II was obtained. All external conditions were identical in getting the two curves, and the purification of the gas was the same except for the drying, which was more complete when curve 2 was obtained. The difference between the two results may possibly be due to an adsorbed layer of water on the test body. 1 Hammar, G. W., this issue of these

PROCZEDINGS.

2Glaser, A., Annalen der Physik, 75, p. 459.

STRIPPED ATOMS OF THE FIRST LONG PERIOD By R. C. GIBBS AND H. E. WHITE DZPARTMZNT OF PHYsIcs, CORNELL UNIVURSITY

Communicated August 25, 1926

In a previous report' on stripped atoms of the first long period in the periodic table, the so-called irregular doublet law was shown to hold for the first lines of the principal series of each element which involve jumps -between levels of the same total quantum number when the first of these stripped-off electrons is being bound. We have since been able to locate -the first lines of the diffuse series for the stripped atoms of the same elemnents which consist as in Call of an inverted doublet with a satellite. As the so-called irregular law holds only for jumps between levels having -the same total quantum number, the 42P1,2 to 32D2,3 jumps will not be expected to follow this law, for here the 42P1,2 levels according to Sommerfeld have a total quantum number 4, and the 32D2,3 levels a total quantum number 3. Since recent advances in spectrum analysis has demanded a more complex system of notation for spectral terms, we use in this report the notation introduced by Russell and Saunders2 and now being used by many others. In the above terms, the integer prefixed to the term gives the total quantum number of the orbit, the capitalized letter gives the azimuthal quantum

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PHYSICS: GIBBS AND. WHITE

number, i.e., the type of term and the superscript to the left and subscript to the right give the multiplicity of the term and the corresponding Land6 inner quantum numbers, respectively. From Fowler's report, "Ser- 2.6 ies in Line Spectra,"3 it has long been known that in KI I / state Call the lowest or normal / and of the atom is a single / / 42S, level and, therefore, re- -.e _ __ _ _ quires the single valence electronto be an "s" electron. In .4___ the Moseley diagram, figure 1, __ it may be seen that the 32D2,3 / levels have changed from the `' third position in KI to the second position in Cal,, while .6 _.__ with the new data on scandium they have shifted to the poScm I CaE Vv K sition of lowest energy level T;1 FIGURE 1 in Scl11. It is apparent that here is a strong confirmation that the "d" electron is the most tightly bound electron through this group of elements. This TABLE 1

SCANDuminI INT.

A'

v

2

2734.83

36565.3

3

2699.81

37039.6

3

2012.9

49680

TRMS

42P2"-42SI 474.3

42P1-42S1

42P2-52S1 473

5

1993.9

50153

42P1..-52S1

4

1610.3

62100

5 1

1603.3 1598.0

62372 ......... 478 206 62578Jj.

32D2-42P1 32D3-42P32D2-42P2

TERM

VALU

42S 42p, 42P2

32D3

178080.2 141514.9 141040.6 203618.6 203412.6

1.274 1. 13& 1.134 1.362 1.361

52S,

91362.0

0.912

32D2

very beautifully confirms also the Bohr-Stoner scheme of the building-on of the various electrons of different elements in this group, and fits exactlyr

PHYSICS: GIBBS AND WHITE

600

PRoe. N. A.. S.

as would be expected into the new theory brought forward by Hund4 on the elements of the first long period. The position of the lines in ScIII were predicted at 1' = 62,000 by an almost linear extrapolation of the 32D2 term, the 42P1,2 terms being known from previous work.' Ireton,5 having photographed the spark spectrum of scandium in this region using a vacuum spectrograph, gave us the conTABLE 2 TITANIMITv INT.

A

6

2103.79

47533.3

6 .

2068.22

48350.8

781.79 779.09 776.85

127911.6 128354.9 128724.9

TERMS

42P2-42S1 817.5

5 8 1

42P,-42S,

1

TERM

VALUE

42S, 42P1

281840 234307 233489 362219 361844

42P2 32D2 32DS

3'D2-42P,

* - - @-813.3 .-..370.0 -

32D,&-42P 32D2-4'P2 Vs,R 1.602

1.461 1.442 1.817 1.816

TABLE 3 VANADIUMV TERMS

LNT.

7

1715.82

58281.1

7

1679.36

59546.5

4 5 2

484.47 482.99

206411.1 207043.6 207688.6

42P2-425, 1265.4

-481.49

TERM

VALUES

42S,

408370 350089 348824 556512 555867

42p, *32D2 32D3

42P, -42'S

32D2-42P,

21277.5 I

645.0

3'Ds-4'P,

32D2-4'P2 1.929 1.786 1.783 2.252 2.250

necting link between the data given by Fowlers for KI and Ca,, and the data we already had on titanium and vanadium. In ScllI the jump from 42PI,2 to 32D2,, results in an inverted diffuse doublet with one satellite, having an outside separation the same as the principal lines 42S,-42PI,2. These three lines were easily identified by their relative intensities and their khown separation. These terms plotted

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PHYSICS: GIBBS A ND WHITE

601

Moseley diagram show that -I/v7iR progresses almost linearly with atomic number as was previously expected. Having worked out the spectrum of titanium and vanadium below wavelength 1500 A.U., the similar jumps for Tiiv and Vv were readily identified. The lines thus found are given in tables 1, 2 and 3 with their frequencies, and the term values computed from the 42P1,2 and 42S1 terms given in a previous report.' With these short wave-lengths the frequencies of lines rise so rapidly with decreasing wave-lengths that fairly high dispersion and good resolution is necessary for accurate measurements, so that the observed Avs, here given, are well within the experimental error of measurement. It is worthy of note that even in the case of Vv, where four electrons have been completely removed from the atom, the lines arising from the last electron are relatively strong except for the line of shortest wave-length which is fairly weak. Recently, Bowen and Millikan,7 working on the second long period, have identified the corresponding levels in Ytl11 and Zriv which show exactly the same behavior as in the first long period, namely, that the "d" electrons are the tightest bound causing the 42D2,3 term values to rise above the others in Ytl1. In our report8 on the second and third long periods only the 2P1,2 and 2S1 levels had been located. However, we have now identified the 52D2,r62P1,2 lines in La,,, which show again that the 52D2,3 term values rise above the 62P1,2 and 62S1 term values and, therefore, that the "d" electrons are more tightly bound than either the "p" or the "s" electrons. As yet we have not been able to locate the 2F levels of the first long period because of their small wave-length separations even though their positions can be predicted to within two or three Angstr6ms of their correct value. We hope by photographing them in higher orders with a new vacuum spectrograph now being constructed to identify and establish the 2F terms. 1 Gibbs, R. C. and White, H. E., Proc. Nat. Acad. Sci., 12, p. 448, 1926. 2 Russell, H. N., and Saunders, F. A., Astrophys. Journ., 61, p. 66, 1925.

on the

3Fowler, A., A Series in Line Spectra, Fleetway Press, 1922. 4 Hund, F., Zs. f. Phys., 33, p. 345, 1925. Ireton, H. J. C., Trans. Roy. Soc. of Canada, 18, p. 103, 1924. 6 From plates photographed by us at the Norman Bridge Laboratory in Pasadena. 7 Bowen, I. S., and Millikan, R. A., Data not yet published, but mentioned here with their kind permission. Will appear in Physic. Rev., Nov., 1926. 8 Gibbs, R. C., and White, H. E., Proc. Nat. Acad. Sci., 12, p. 551, 1926.