John J. Hopfield (spectroscopist)

John Joseph Hopfield (8 August 1891 – 8 January 1953) was a Polish-American spectroscopist, discoverer of the Hopfield bands of oxygen and co-discoverer of the Lyman-Birge-Hopfield bands of nitrogen. Hopfield's major research pursuits included vacuum ultraviolet spectroscopy and solar ultraviolet spectroscopy. He was well known in these disciplines. Hopfield published frequently and produced several patents.

Life and education

Hopfield was born in Poland in 1891. In 1917 he received an A.B. from Syracuse University. From 1918 to 1920 he continued at Syracuse as a Physics Instructor.

For the term 1920–1921 Hopfield was awarded a Whiting Research Fellowship. From 1921 to 1923 he was Associate in Physics, then from 1923 to 1925 was Instructor in Physics, and in 1925 appointed to Assistant Professor of Physics at the University of California, Berkeley.

Hopfield earned his Ph.D. in Physics, Chemistry in 1923 from the University of California, Berkeley. His advisor was Raymond T. Birge and his thesis subject was: Spectra of hydrogen, nitrogen, and oxygen in the extreme ultra-violet.^[1]

At Berkeley, a graduate student working under Hopfield was Gerhard Heinrich Dieke.

In 1928 John Joseph Hopfield received a Guggenheim Fellowship appointment: "for experimental study of the Zeeman effect on the infra-red spectra of oxygen and nitrogen with reference to the classification of the extreme ultra-violet spectra of these elements, chiefly with Professor F. Paschen, of Berlin." ^[2]

By the time he left Berlin in 1929, the stock market crash and depression had ended most new faculty hiring. Purdue University appointed him as a National Research Council Fellow for two years. He next was employed in creating the physics exhibit for the 1933 ‘Century of Progress’ World’s Fair in Chicago, followed by a position with the Libby-Owens-Ford glass company in Toledo Ohio. With the onset of WWII, physicists were again in great demand, and he moved to Washington DC to participate in war-related research. The end of his career was spent at the Johns Hopkins Applied Physics Laboratory and at the Naval Research Laboratory in the Optics Division in [[Washington, D.C>]]. On 8 January 1953, Hopfield died after a brief illness.

Known for and credits

John J. Hopfield is known and credited for:

• Hopfield bands, one of the important molecular oxygen absorption bands
  • the Hopfield bands, very strong, between about 67 and 100 nanometres in the ultraviolet
• Lyman-Birge-Hopfield bands (LBH bands), one of the important molecular nitrogen absorption bands

Accolades

• Accolades garnered from correspondence from Raymond Birge to John Van Vleck, 1929: "Hopfield is doing the best vacuum spectroscopy of anyone in the world." ^[3]

Select publications

• Ultraviolet Absorption and Emission Spectra of Carbon Monoxide^[4]
• The Ultra-Violet Band Spectrum of Nitrogen^[5]
• New Ultra-Violet Spectrum of Helium^[6]
• Absorption and Emission Spectra in the Region λ 600-1100.^[7]
• New Oxygen Spectra in the Ultraviolet and new Spectra in Nitrogen^[8]
• Preparation of Schumann plates^[9]
• The Ultraviolet Spectrum of the Sun from V-2 Rockets^[10]

Patents

• HOPFIELD^[11]
• Manufacture of multiple glass sheet glazing units^[12]
• Uniting of glass to glass and metals to glass^[13]
• Multiple glass sheet glazing unit and method of making the same^[14]
• Multiply glass sheet glazing unit^[15]
• Method of fabricating multiple glass sheet glazing units^[16]

References

1. University of California, Berkeley, 1923–24. Berkeley, California: University of California Press. 1924. p. 214.
2. "John Simon Guggenheim Memorial Foundation". John Simon Guggenheim Memorial Foundation. Retrieved 2 August 2014.
3. Clayton Gearhart (April 2008). "David Dennison, the specific heat of hydrogen, and the discovery of nuclear spin: Experimental foundations" (PDF). American Physical Society. Retrieved 2 August 2014.
4. Hopfield, J. J.; R. T. Birge (1927). "Ultraviolet Absorption and Emission Spectra of Carbon Monoxide". Physical Review. 29: 922. doi:10.1103/PhysRev.29.901.
5. Birge, R. T.; J. J. Hopfield (1928). "The Ultra-Violet Band Spectrum of Nitrogen". The Astrophysical Journal. 68: 257. doi:10.1086/143142.
6. Hopfield, John J. (1930). "New Ultra-Violet Spectrum of Helium". The Astrophysical Journal. 72: 133. doi:10.1086/143271.
7. Hopfield, John J. (1930). "Absorption and Emission Spectra in the Region λ 600-1100". Physical Review. 35 (9): 1133. doi:10.1103/physrev.35.1133.
8. Hopfield, J. J. (1930). "New Oxygen Spectra in the Ultraviolet and new Spectra in Nitrogen". Physical Review. 36: 789–790. doi:10.1103/physrev.36.783.
9. Hopfield, J. J.; E. T. S. Appleyard (1932). "A Simplified Method of Preparing Schumann Plates". JOSA. 22 (9): 488–495. doi:10.1364/josa.22.000488.
10. ((cite journal | title=The Ultraviolet Spectrum of the Sun from V2 Rockets |author1=Hopfield, J. J. |author2=Clearman, H. E.| journal=Phys. Rev. |date=1948|volume=73 | issue=9 | pages=877-884 | doi=10.1103/PhysRev.73.877))
11. Hopfield, John J. (28 February 1933). HOPFIELD. U.S. Patent No. 1,899,804. Washington, D.C.: U.S. Patent and Trademark Office.
12. Hopfield, John J. (3 September 1940). Manufacture of multiple glass sheet glazing units. U.S. Patent No. 2,213,395. Washington, D.C.: U.S. Patent and Trademark Office.
13. Hopfield, John J. (14 January 1941). Uniting of glass to glass and metals to glass. U.S. Patent No. 2,228,352. Washington, D.C.: U.S. Patent and Trademark Office.
14. Haven, Charles D.; John J. Hopfield (18 March 1941). Multiple glass sheet glazing unit and method of making the same. U.S. Patent No. 2,235,680. Washington, D.C.: U.S. Patent and Trademark Office.
15. Haven, Charles D.; John J. Hopfield (18 March 1941). Multiple glass sheet glazing unit. U.S. Patent No. 2,235,681. Washington, D.C.: U.S. Patent and Trademark Office.
16. Hopfield, John J. (14 December 1943). Method of fabricating multiple glass sheet glazing units. U.S. Patent No. 2,336,544. Washington, D.C.: U.S. Patent and Trademark Office.