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The photo-electric threshold for mercury

Kazda, C. B. (1925) The photo-electric threshold for mercury. Physical Review, 26 (5). pp. 643-654. ISSN 0031-899X. http://resolver.caltech.edu/CaltechAUTHORS:KAZpr25

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Abstract

In order to insure a perfectly clean surface of mercury for test, the apparatus was arranged so that carefully purified mercury flowed intermittently into a shallow iron cup and out through an overflow opening at the surface back into an electrically heated still. Direct observation showed that with such a flow the surface cleans itself of any added contamination very quickly. Also, the results for the wave-length limit were found to be independent of the rate of flow, to a rate far below that normally used, and also unaffected by the presence of gases (air, H2, O2, He and CO2) and even of traces of water vapor in the photochamber. The photo-currents to a copper oxide receiver were measured by means of a quadrant electrometer to within about 1 percent for various Hg lines from a Cooper-Hewitt quartz mercury arc, correction being made for stray light by means of intermediate readings. This arc operated at 92-93 volts with 2.1 amp., was constant to 1 percent. Intensity measurements accurate to 1 percent were made by means of a vacuum thermopile connected to a d'Arsonval galvanometer (sensitivity 10(-9) amp.) using a Hilger monochromator to disperse the light and making correction for stray light by taking readings between the lines. Plots of the ratio of corrected photo-current to corrected light intensity as a function of wave-length give the threshold at 2735A. The corresponding photo-electric work function is 4.52 volts. This result is free from the objections raised to those of previous observers and seems clearly to be the evaluation of an intrinsic property of mercury uncontaminated by surface impurities.


Item Type:Article
Additional Information:©1925 The American Physical Society. Received 20 November 1923; revised 20 August 1925. In conclusion, I wish to thank Professor Millikan for suggesting this work with flowing mercury and for putting the facilities of the laboratory at my disposal.
Record Number:CaltechAUTHORS:KAZpr25
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:KAZpr25
Alternative URL:http://dx.doi.org/10.1103/PhysRev.26.643
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2436
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:04 Apr 2006
Last Modified:26 Dec 2012 08:49

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