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The Photo-Electric Threshold and the Heat of Dissociation of the Potassium Molecule

Published online by Cambridge University Press:  24 October 2008

R. W. Ditchburn
R. W. Ditchburn
Affiliation:
Trinity College, Isaac Newton Student
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Abstract

The absorption curves and the photo-ionisation experiments agree to give a value for the molecular photo-electric threshold of λ 2555 ± 20 a.u. If our view of the ionisation process is correct, the energy of dissociation is 0·505 ∓ ·01 volts. If the picture of the ionisation process is wrong, the energy of dissociation may be a little lower (a few hundredths of a volt). The corresponding heat of dissociation is 11400 calories. In the range of temperature (200° C. to 500° C.) generally used in experiments on potassium vapour, the fraction associated varies from 10−4 to 10−2. An equation for calculating the fraction associated at any temperature is given by the writer in an earlier paper.

Type
Research Article
Information
Mathematical Proceedings of the Cambridge Philosophical Society , Volume 24 , Issue 2 , April 1928 , pp. 320 - 327
Copyright
Copyright © Cambridge Philosophical Society 1928

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