Open AccessThe thermionic work-functions and photo-electric thresholds of the alkali metals
Author(s) -
O. W. Richardson,
A. F. A. Young
Publication year - 1925
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1925.0032
Subject(s) - thermionic emission , alkali metal , tungsten , atmospheric temperature range , work function , function (biology) , thermodynamics , range (aeronautics) , chemistry , work (physics) , mathematics , physics , analytical chemistry (journal) , materials science , quantum mechanics , electron , electrode , organic chemistry , chromatography , evolutionary biology , biology , composite material
That has generally been found that the thermionic currents from solids follow formula AT1/2 e-b/T , where A andb are two constants, over a wide range temperature. So far as this matter is concerned, the same result holds if, index of T is replaced by 2, or, in fact, by any similar low number. For Sample, K. K. Smith has shown in the case of tungsten that such a formula such two constants covers the thermionic currents, from 1,050° K to 2300° K, over which range of temperature the currents increase by a factor of about 1012 . appears, however, that the alkali metals—at any rate, under such conditions it is feasible to make experiments on them—do not subscribe to this requirement. If the old values of logi — 2 log T (i = thermionic current, T = absolute temperature) for sodium are plotted against T-1 , it will be found that the curve not a straight line, as is the case with most substances, but is definitely convex towards the origin. This can, in fact, be seen from fig. 21, p. 539, the paper, which is a plot of logi — 1/2 log T, since this function behaves similarly to logi — 2 log T. This shows that the equationi = CT2 e -d /T