Editing Franck–Hertz experiment (section)

== References ==
{{reflist |refs=
<ref name=Brandt>{{cite book |title=The harvest of a century: discoveries of modern physics in 100 episodes |first=Siegmund |last=Brandt |chapter=25. The Franck Hertz experiment (1914) |page=272 |publisher=Oxford University Press |year=2008 |isbn=9780191580123 |chapter-url=https://books.google.com/books?id=Zdtnvou-V9cC&pg=PT272}}</ref>
<ref name=Cohen>{{cite book |title=Revolution in Science |url=https://archive.org/details/revolutioninscie00cohe |url-access=registration |first=I. Bernard |last=Cohen |author-link=I. Bernard Cohen |publisher=Belknap Press |year=1985 |isbn=9780674767775 |pages=[https://archive.org/details/revolutioninscie00cohe/page/427 427–428] |quote=In 1912 a young Dane working in Rutherford's laboratory in Manchester proposed a revolutionary new model of the atom. ... What made Bohr's theory difficult to believe in was the idea of discrete and fixed states or orbits, with no intermediate states being possible.}}</ref>
<ref name=Demtroeder>{{cite book |title=Atoms, Molecules and Photons: An Introduction to Atomic-, Molecular- and Quantum Physics |first=Wolfgang |last=Demtröder |publisher=Springer |year=2010 |isbn=9783642102981 |chapter=3.4.4 Franck–Hertz experiment |pages=118–120 |chapter-url=https://books.google.com/books?id=vbc5mA7OEuYC&pg=PA118}}</ref>
<ref name=FH1>{{cite journal |first1=J. |last1=Franck |first2=G. |last2=Hertz |title=Über Zusammenstöße zwischen Elektronen und Molekülen des Quecksilberdampfes und die Ionisierungsspannung desselben |language=de |trans-title=On the collisions between electrons and molecules of mercury vapor and the ionization potential of the same |journal=Verhandlungen der Deutschen Physikalischen Gesellschaft |year=1914 |volume=16 |pages=457–467 |url=https://www.dpg-physik.de/presse/veranstaltungen/tagungen/2014/pdf/Franck-Hertz-Experiment-VH1914.pdf |access-date=2017-01-21 |archive-date=2017-02-02 |archive-url=https://web.archive.org/web/20170202002826/https://www.dpg-physik.de/presse/veranstaltungen/tagungen/2014/pdf/Franck-Hertz-Experiment-VH1914.pdf |url-status=dead }} A translation of this paper is given in {{cite book |last1=Boorse |first1=Henry A. |last2=Motz |first2=Lloyd |title=The World of the Atom |volume=1 |chapter=46. The Quantum Theory is Tested |pages=766–778 |publisher=Basic Books |year=1966 |oclc=534667 }} In their initial papers, Franck and Hertz interpreted the 4.9&nbsp;V potential associated with inelastic electron-mercury collisions as indicative of the ionization potential of mercury. The relationship to the Bohr model of atoms emerged somewhat later.</ref>
<ref name=FH2>{{cite journal |first1=J. |last1=Franck |first2=G. |last2=Hertz |title = Über die Erregung der Quecksilberresonanzlinie 253,6&nbsp;μμ durch Elektronenstöße |language=de |trans-title=On the excitation of mercury resonance lines at 253.6&nbsp;nm by electron collisions |journal = Verhandlungen der Deutschen Physikalischen Gesellschaft |year = 1914 |volume=16 |pages=512–517}} The symbol μμ is an outdated, rare usage for a [[nanometre]]. This article was reprinted in {{cite book |title=Die Elektronenstoßversuche |first1=James |last1=Franck |first2=Gustav |last2=Hertz |first3=Armin |last3=Hermann |author3-link=:de:Armin Hermann  |location=München |publisher=E. Battenberg |year=1967 |oclc=9956175}}</ref>
<ref name=Franck60>In 1960, Franck explained that he and Hertz were unaware of Bohr's ideas when their two 1914 papers were presented. Franck gave his remarks as the epilogue to the film on the Franck–Hertz experiment from the [[Physical Science Study Committee]] (1960). The film is available online; see {{cite AV media |people=Byron L. Youtz (narrator); James Franck (epilogue); Jack Churchill (director) |year=1960 |title=Franck-Hertz experiment |minutes=25 |url=https://archive.org/details/FranckHertzExperiment |medium=16 mm film |publisher=Educational Services |oclc=4949442 |access-date=2014-07-01}}. A transcript of the epilogue was published shortly after the film was made; see  {{cite journal |last=Holton |first=Gerald |title=On the recent past of physics |year=1961 |journal=American Journal of Physics |volume=61 |issue=12 |pages=805–810 |doi=10.1119/1.1937623 |bibcode = 1961AmJPh..29..805H |doi-access=free }}</ref>
<ref name=Lemmerich>{{cite book |title=Science and Conscience: The Life of James Franck |first=Jost |last=Lemmerich |others=Translated by Ann Hentschel |publisher=Stanford University Press |date=2011 |isbn=9780804779098 |pages=45–50 |quote=Then two papers by Franck and Hertz about measurements on vaporized mercury that were to enter their names on the rolls of the history of physics appeared in quick succession. The first paper was presented by Gustav Hertz at the German Physical Society's meeting on 24 April 1914, the second by James Franck on May 22. (p. 45) |url=https://books.google.com/books?id=tCoY5WAjHPQC&pg=PA45}} Translation of {{cite book |title=Aufrecht im Sturm der Zeit : der Physiker James Franck, 1882–1964 |publisher=Verlag für Geschichte der Naturwissenschaften und der Technik |date=2007 |isbn=9783928186834 |oclc=234125038}}</ref>
<ref name=Melissinos>{{cite book |title=Experiments in Modern Physics |first1=Adrian Constantin |last1=Melissinos |first2=Jim |last2=Napolitano |chapter=1.3 The Franck–Hertz Experiment |pages=10–19 |publisher=Gulf Professional Publishing |year=2003 |isbn=9780124898516 |chapter-url=https://books.google.com/books?id=eTK1lX_oCUcC&pg=PA10}} This reference incorrectly suggests that Franck and Hertz were aware of the Bohr model when they published their experiments. Franck himself remarked on this in an interview late in his life; see {{cite journal |last=Holton |first=Gerald |title=On the recent past of physics |year=1961 |journal=American Journal of Physics |volume=61 |issue=12 |pages=805–810 |doi=10.1119/1.1937623|bibcode = 1961AmJPh..29..805H |doi-access=free }}</ref>
<ref name=Nuffield>For converting electron volts to electron speeds, see {{cite web |title=The speed of electrons |publisher=[[Nuffield Foundation]] |work=Practical Physics |url=http://www.nuffieldfoundation.org/practical-physics/speed-electrons |access-date=2014-04-18}}</ref>
<ref name=Pais>{{cite book |title=Subtle is the Lord: The Science and the Life of Albert Einstein |publisher=Oxford University Press |year=1982 |isbn=9780191524028 |last=Pais |first=Abraham |page=[https://archive.org/details/subtleislordscie00pais/page/381 381] |url=https://archive.org/details/subtleislordscie00pais|url-access=registration }} The energy ''E'' of a photon is the product of the [[Planck constant]] ''h'' and the ratio ''c''/''λ'' of the speed of light ''c'' and the wavelength ''λ''.</ref>
<ref name=Pais2>{{cite book |title=Twentieth Century Physics |volume=1 |editor1-last=Brown |editor1-first=Laurie M. |editor1-link=Laurie Brown (physicist) |editor2-first=Abraham |editor2-last=Pais |editor3-first=Brian |editor3-last=Pippard |editor3-link=Brian Pippard |publisher=American Institute of Physics Press |year=1995 |chapter=Introducing Atoms and Their Nuclei |last=Pais |first=Abraham |author-link=Abraham Pais |page=89 |quote=Now the beauty of Franck and Hertz's work lies not only in the measurement of the energy loss ''E''<sub>2</sub>-''E''<sub>1</sub> of the impinging electron, but they also observed that, when the energy of that electron exceeds 4.9 eV, mercury begins to emit ultraviolet light of a definite frequency ''ν'' as defined in the above formula. Thereby they gave (unwittingly at first) the first direct experimental proof of the Bohr relation! |isbn=9780750303101}} The frequency ''ν'' is related to the wavelength ''λ'' of light by the formula ''ν'' = ''c''/''λ'', where ''c'' = {{val|2.99|e=8|u=m/s}} is the speed of light in vacuum.</ref>
<ref name=Rice>{{cite web |url=https://www.nasonline.org/directory-entry/james-franck-z6f97a/ |title=James Franck 1882–1964: A Biographical Memoir |year=2010 |publisher=[[National Academy of Sciences]] (US) |last1=Rice |first1=Stuart A. |author-link1=Stuart A. Rice |last2=Jortner |first2=Joshua |author-link2=Joshua Jortner |quote=Our understanding of the world was transformed by the results of this experiment; it is arguably one of the most important foundations of the experimental verification of the quantum nature of matter. |page=6}}</ref>
<ref name=Thornton>In their original experiment, Franck and Hertz used platinum for both the cathode and the grid. When different materials are used for the electrodes, there is an additional contribution to the kinetic energy beyond the externally applied voltage. See {{cite book |title=Modern Physics for Scientists and Engineers |first1=Stephen |last1=Thornton |first2=Andrew |last2=Rex |edition=4 |pages=154–156 |url=https://books.google.com/books?id=u0gmQ07nyyMC&pg=PA154 |publisher=Cengage Learning |year=2012 |isbn=9781133103721 }}</ref>
<ref name=Thornton2>{{cite book |title=Modern Physics for Scientists and Engineers |first1=Stephen |last1=Thornton |first2=Andrew |last2=Rex |edition=4 |pages=154–156 |url=https://books.google.com/books?id=u0gmQ07nyyMC&pg=PA154 |publisher=Cengage Learning |year=2012 |isbn=9781133103721 }}</ref>
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