Abstract

Photographs are shown which are the images of atoms of helium, neon and argon as obtained by x-ray diffraction, magnified about 2×108 times. The images are obtained by photographing a rotating template whose shape is calculated by a mathematical transformation of our measured values of the x-rays scattered by the respective gases. This mathematical-mechanical procedure corresponds to the lens which forms the image when a microscope is used. The images formed by our procedure should be true representations of the electron distributions in the atom, except for the limited resolving power and certain minor aberrations. The photographs show the helium atom as a diffusely continuous region filled with electricity. In neon, the inner group of K electrons is clearly distinguishable from the L electron group. The resolving power is insufficient to distinguish the K and L groups of electrons in argon, but does separate these from the M electrons. The appearance of these atoms is in good accord with modern quantum theory of atomic structure.

© 1934 Optical Society of America

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References

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  1. A. A. Michelson, Studies in Optics (University of Chicago Press, 1928), p. 60.
  2. W. L. Bragg, Zeits. f. Krist. 70, 489 (1929); The Crystalline State (Macmillan, 1934), p. 227. The photographs obtained by Bragg do not show as great detail in the structure of the atoms as those here presented. This is doubtless due in part to the fact that the photographic method of obtaining the image which he uses must result in considerable loss of detail; but there is also the essential limitation of the crystal method that the atoms which are photographed are in thermal motion about their neutral positions. This, of course, makes a blurred image. Our method, being based on diffraction by gaseous molecules, assumes a random arrangement, and is hence unaffected by the thermal motion. Thus our practical resolving power almost equals the theoretical value.
  3. E. O. Wollan, Phys. Rev. 37, 862 (1931).
    [Crossref]
  4. A. H. Compton, Phys. Rev. 35, 925 (1930).
    [Crossref]
  5. For a more detailed account of these results, cf. E. O. Wollan, Rev. Mod. Phys. 4, 243 (1932).
    [Crossref]
  6. The x-ray scattering data on which the mercury atom photograph is based, were obtained by P. Scherrer and A. Stager, Helv. Phys. Acta 1, 518 (1928).
  7. H. E. White, Phys. Rev. 37, 1423 (1931).

1932 (1)

For a more detailed account of these results, cf. E. O. Wollan, Rev. Mod. Phys. 4, 243 (1932).
[Crossref]

1931 (2)

E. O. Wollan, Phys. Rev. 37, 862 (1931).
[Crossref]

H. E. White, Phys. Rev. 37, 1423 (1931).

1930 (1)

A. H. Compton, Phys. Rev. 35, 925 (1930).
[Crossref]

1929 (1)

W. L. Bragg, Zeits. f. Krist. 70, 489 (1929); The Crystalline State (Macmillan, 1934), p. 227. The photographs obtained by Bragg do not show as great detail in the structure of the atoms as those here presented. This is doubtless due in part to the fact that the photographic method of obtaining the image which he uses must result in considerable loss of detail; but there is also the essential limitation of the crystal method that the atoms which are photographed are in thermal motion about their neutral positions. This, of course, makes a blurred image. Our method, being based on diffraction by gaseous molecules, assumes a random arrangement, and is hence unaffected by the thermal motion. Thus our practical resolving power almost equals the theoretical value.

1928 (1)

The x-ray scattering data on which the mercury atom photograph is based, were obtained by P. Scherrer and A. Stager, Helv. Phys. Acta 1, 518 (1928).

Bragg, W. L.

W. L. Bragg, Zeits. f. Krist. 70, 489 (1929); The Crystalline State (Macmillan, 1934), p. 227. The photographs obtained by Bragg do not show as great detail in the structure of the atoms as those here presented. This is doubtless due in part to the fact that the photographic method of obtaining the image which he uses must result in considerable loss of detail; but there is also the essential limitation of the crystal method that the atoms which are photographed are in thermal motion about their neutral positions. This, of course, makes a blurred image. Our method, being based on diffraction by gaseous molecules, assumes a random arrangement, and is hence unaffected by the thermal motion. Thus our practical resolving power almost equals the theoretical value.

Compton, A. H.

A. H. Compton, Phys. Rev. 35, 925 (1930).
[Crossref]

Michelson, A. A.

A. A. Michelson, Studies in Optics (University of Chicago Press, 1928), p. 60.

Scherrer, P.

The x-ray scattering data on which the mercury atom photograph is based, were obtained by P. Scherrer and A. Stager, Helv. Phys. Acta 1, 518 (1928).

Stager, A.

The x-ray scattering data on which the mercury atom photograph is based, were obtained by P. Scherrer and A. Stager, Helv. Phys. Acta 1, 518 (1928).

White, H. E.

H. E. White, Phys. Rev. 37, 1423 (1931).

Wollan, E. O.

For a more detailed account of these results, cf. E. O. Wollan, Rev. Mod. Phys. 4, 243 (1932).
[Crossref]

E. O. Wollan, Phys. Rev. 37, 862 (1931).
[Crossref]

Helv. Phys. Acta (1)

The x-ray scattering data on which the mercury atom photograph is based, were obtained by P. Scherrer and A. Stager, Helv. Phys. Acta 1, 518 (1928).

Phys. Rev. (3)

H. E. White, Phys. Rev. 37, 1423 (1931).

E. O. Wollan, Phys. Rev. 37, 862 (1931).
[Crossref]

A. H. Compton, Phys. Rev. 35, 925 (1930).
[Crossref]

Rev. Mod. Phys. (1)

For a more detailed account of these results, cf. E. O. Wollan, Rev. Mod. Phys. 4, 243 (1932).
[Crossref]

Zeits. f. Krist. (1)

W. L. Bragg, Zeits. f. Krist. 70, 489 (1929); The Crystalline State (Macmillan, 1934), p. 227. The photographs obtained by Bragg do not show as great detail in the structure of the atoms as those here presented. This is doubtless due in part to the fact that the photographic method of obtaining the image which he uses must result in considerable loss of detail; but there is also the essential limitation of the crystal method that the atoms which are photographed are in thermal motion about their neutral positions. This, of course, makes a blurred image. Our method, being based on diffraction by gaseous molecules, assumes a random arrangement, and is hence unaffected by the thermal motion. Thus our practical resolving power almost equals the theoretical value.

Other (1)

A. A. Michelson, Studies in Optics (University of Chicago Press, 1928), p. 60.

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Figures (7)

Fig. 1
Fig. 1

Intensity of x-rays scattered by gases. I, helium; II, neon; III, argon.

Fig. 2
Fig. 2

Radial electron distribution in helium. Solid line from experiment, broken line from wave mechanics according to Hartree.

Fig. 3
Fig. 3

Radial electron distribution in neon. Solid line from experiment, broken line from wave mechanics according to Hartree.

Fig. 4
Fig. 4

Radial electron distribution in argon. Solid line from experiment, broken line from wave mechanics according to Hartree.

Figs. 6, 7 and 8
Figs. 6, 7 and 8

Figs. 6, 7 and 8 show “appearance” of atoms of helium, neon and argon, respectively, as observed with x-rays of wave-length 0.71A and a spectrometer working to an angle of 90°.

Fig. 9
Fig. 9

Fig. 9 shows “appearance” of mercury atom, based on Thomas-Fermi electron distribution, as supported by x-ray scattering experiments. This picture represents closely, except for differences in scale, the “appearance” of any atom heavier than argon.

Equations (6)

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U ( a ) = 2 Z a π 0 { S - R Z - R } 1 2 k sin ( a k ) d k ,
λ / 2 = 2 δ sin ( φ / 2 )
δ = λ / 4 sin ( φ / 2 ) ,
P ( r ) · r · d θ · d r = 2 0 ρ · r · d θ · d r · d h ,
P ( r ) = 1 2 π r U ( a ) a ( a 2 - r 2 ) 1 2 d a .
P ( r ) = Z π 2 r 0 { S - R Z - R } 1 2 k sin ( a k ) ( a 2 - r 2 ) 1 2 d k d a ,