Helmut Hönl

Helmut Hönl (1903 in Mannheim, Germany – 1981) was a German theoretical physicist who made contributions to quantum mechanics and the understanding of atomic and molecular structure.

From 1921 to circa 1923, Hönl studied at the University of Heidelberg and the University of Göttingen, followed by the University of Munich, where he studied under Arnold Sommerfeld. He was granted his doctor of philosophy in 1926. In 1929, he became assistant to Paul Peter Ewald at the Stuttgart Technische Hochschule until 1933, after which he was a Privatdozent. [ [http://www.amphilsoc.org/library/guides/ahqp/ Author Catalog: Hönl] – American Philosophical Society.]

Even before acquiring his doctorate at Munich, Hönl had done seminal work which contributed to the advancement of quantum mechanics and the understanding of atomic and molecular structure and spectra. [ Helmut Hönl “The intensity of Zeeman components” (Translated from the German) "Zeitschrift für Physik" 31 (1925) 340-354.] [ Arnold Sommerfeld and Helmut Hönl "Über die Intensität der Multiplett-Linien", "Sitzungsberichte der Preußischen Akademie der Wissenschaften. Physikalisch-mathematische Klasse." 141-161 (1925) as cited in [http://www.lrz-muenchen.de/~Sommerfeld/WWW/AS_Bib1.html Arnold Sommerfeld Bibliography] – Sommerfeld Project.] [ Helmut Hönl “The intensity problem of spectral lines” (Translated from the German) "Annalen der Physik" 79 (1926) 273-323.] Some of his work was done in collaboration with Fritz London. [ Helmut Hönl and Fritz London “The intensities of the band lines” (Translated from the German) "Zeitschrift für Physik" 33 (1925) 803-809.] As is the case in any fast developing field with a high level of interest, others independently make similar findings. This was the case with his work on the intensity of Zeeman effect spectral lines. Both Hönl [ Helmut Hönl “The intensity of Zeeman components” (Translated from the German) "Zeitschrift für Physik" 31 (1925) 340-354.] and Samuel Goudsmit and Ralph de Laer Kronig [ Goudschmit, Samuel and Ralph de Laer Kronig "Naturwiss." 13 (1925) 90.] published results in 1925. Their work was promptly put into use. In the first paper of the trilogy [ W. Heisenberg, “Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen,” "Zeitschrift für Physik", 33, 879-893, 1925 (received July 29, 1925). [English translation in: B. L. van der Waerden, editor, "Sources of Quantum Mechanics" (Dover Publications, 1968) ISBN 0-486-61881-1 (English title: "Quantum-Theoretical Re-interpretation of Kinematic and Mechanical Relations").] ] [ M. Born and P. Jordan, "Zur Quantenmechanik," "Zeitschrift für Physik", 34, 858-888, 1925 (received September 27, 1925). [English translation in: B. L. van der Waerden, editor, "Sources of Quantum Mechanics" (Dover Publications, 1968) ISBN 0-486-61881-1] ] [ M. Born, W. Heisenberg, and P. Jordan, “Zur Quantenmechanik II,” "Zeitschrift für Physik", 35, 557-615, 1925 (received November, 1925). [English translation in: B. L. van der Waerden, editor, Sources of Quantum Mechanics (Dover Publications, 1968) ISBN 0-486-61881-1] ] which launched the matrix mechanics formulation of quantum theory in 1925, Werner Heisenberg, a former student of Sommerfeld, working with Max Born at the University of Göttingen, used the work of Hönl, Kronig, and Goudsmit, referring to it as the “"Goudsmit-Kronig-Hönl" formula.” [van der Waerden, 1968, p. 274.]

At this time, there were three centers of development for quantum mechanics and the interpretation of atomic and molecular structure, based on atomic and molecular spectroscopy, especially the Sommerfeld-Bohr model: the Theoretical Physics Institute at the University of Munich, under Arnold Sommerfeld, the Institute of Theoretical Physics at the University of Göttingen, under Max Born, and the Institute of Theoretical Physics, under Niels Bohr. These three institutes effectively formed a consortium for the exchange of assistants and researchers. Furthermore, with Sommerfeld educating such capable physicists, when they were called to other facilities, they effectively became extensions of Sommerfeld’s Institute of Theoretical Physics. [ Mehra, Volume 5, Part 1, 2001, p. 249.]

This was the case with Hönl when he went to the Stuttgart Technische Hochschule to work with Paul Peter Ewald, who received his Ph.D. under Sommerfeld and became ordinarius professor of theoretical physics at Stuttgart Technische Hochschule in 1921. [ Ewald was at Stuttgart until 1937. [http://www.amphilsoc.org/library/guides/ahqp/ Author Catalog: Ewald] – American Philosophical Society .] [ Mehra, Volume 5, Part 1, 2001, p. 249.] At Stuttgart, Ewald and Hönl worked on the quantum theory atomic and molecular structure and solid-state physics. They developed a theoretical model of electron densities and the atomic scattering factor in solids. [ P. P. Ewald and H. Hönl "The x-ray interferences in diamond as a wave-mechanical problem. Part I." (English translation from the German) "Annalen der Physik" 25 (4): 281-308, 1936.] [ P. P. Ewald and H. Hönl "X-ray interference in diamonds as problem of wave mechanics. Part II Analysis of linear atomic chains." (English translation from the German) "Annalen der Physik" 26 (8): 673-696, 1936.] [ See ”Chapter 20 Germany” by E. E. Helnner and P. P. Ewald in: Ewald, P. P., editor [http://www.iucr.org/iucr-top/publ/50YearsOfXrayDiffraction/ "50 Years of X-Ray Diffraction"] (Reprinted in pdf format for the IUCr XVIII Congress, Glasgow, Scotland, Copyright © 1962, 1999 International Union of Crystallography).] Their work has been referenced in the literature as the Ewald-Hönl-Brill model [ L. Kleinman and J. C. Phillips Covalent Bonding and Charge Density in Diamond "Phys. Rev." 125 (1962) 819 – 824.] (after the German physicist Rudolf Brill [ R. Brill, H. G. Grimm, C. Herman, and C. Peters "Ann. Physik" 34 (1939) 393.] ).

elected Literature

*Arnold Sommerfeld and Helmut Hönl "Über die Intensität der Multiplett-Linien", "Sitzungsberichte der Preußischen Akademie der Wissenschaften. Physikalisch-mathematische Klasse." 141-161 (1925) as cited in [http://www.lrz-muenchen.de/~Sommerfeld/WWW/AS_Bib1.html Arnold Sommerfeld Bibliography] – Sommerfeld Project.

*Helmut Hönl “The intensity of Zeeman components” (Translated from the German) "Zeitschrift für Physik" 31 340-354 (1925)

*Helmut Hönl and Fritz London “The intensities of the band lines” (Translated from the German) "Zeitschrift für Physik" 33 803-809 (1925)

*Helmut Hönl “The intensity problem of spectral lines” (Translated from the German) "Annalen der Physik" 79 273-323 (1926)

*P. P. Ewald and H. Hönl "The x-ray interferences in diamond as a wave-mechanical problem. Part I." (English translation from the German) "Annalen der Physik" 25 (4): 281-308 (1936)

*P. P. Ewald and H. Hönl "X-ray interference in diamonds as problem of wave mechanics. Part II Analysis of linear atomic chains." (English translation from the German) "Annalen der Physik" 26 (8): 673-696 (1936)

References

*Mehra, Jagdish, and Helmut Rechenberg "The Historical Development of Quantum Theory. Volume 5 Erwin Schrödinger and the Rise of Wave Mechanics. Part 1 Schrödinger in Vienna and Zurich 1887-1925." (Springer, 2001) ISBN 0-387-95179-2

* van der Waerden, B. L., editor, "Sources of Quantum Mechanics" (Dover Publications, 1968) ISBN 0-486-61881-1

Notes