%0 Journal Article %1 PhysRev.21.623 %A Dushman, Saul %D 1923 %I American Physical Society %J Phys. Rev. %K imported physics science thermionic thermionicemission thesis %N 6 %P 623--636 %R 10.1103/PhysRev.21.623 %T Electron Emission from Metals as a Function of Temperature %U http://link.aps.org/abstract/PR/v21/p623 %V 21 %X Electron emission from metals as a function of temperature.—(1) General equation. The emission of electrons from a metal may be considered as thermodynamically equivalent to the evaporation of a monatomic gas, for which an equation is derived on the basis of the Nernst heat theorem. If it is assumed that the specific heat of free electrons in the metal is negligible while the specific heat of the evaporated electrons is the same as that of a monatomic gas, the equation assumes the simple form I=AT2ε-b0 / T, where b0=ϕ0e / k (e is electronic charge, k is the Boltzmann constant, and ϕ0=ϕ-3 / 2kT / e, where ϕ is the Richardson work function). An equation of this form has been suggested before but not on the same theoretical grounds and a different value of A has been obtained. Its chief advantage over the usual Richardson equation, I=A1T1 / 2ε-b / T, where b=ϕe / k, is that A is theoretically a universal constant. (2) The value of the universal emission constant A is computed in two ways. Using the Sackur-Tetrode equation for the chemical constant i0, A comes out 60.2 amp./cm2 deg.2, while the theory of rational units of Lewis, Gibson and Latimer gives 50.2 amp./cm2 deg.2. Recent experimental results of Davisson and Germer, and of Schlichter as well as data obtained by the writer agree with the new equation as well or better than with the old, but the temperature scale is not sufficiently accurately known to distinguish experimentally between the two values of A. (3) The relation between A and the chemical constant i0 (or C0) is derived. Values of the work function in equivalent volts have been computed from the experimentally determined values of b0, for tungsten (4.53), thorium (2.94), molybdenum (4.31), tantalum (4.40), and calcium (2.24) within ½ to 1 per cent. The values for uranium (3.28), zirconium (3.28), yttrium (3.19) and cerium (3.07) are upper limits. In general, the values are lower the larger the atomic volumes. Experimental details will be given later.

@article{PhysRev.21.623, abstract = {Electron emission from metals as a function of temperature.—(1) General equation. The emission of electrons from a metal may be considered as thermodynamically equivalent to the evaporation of a monatomic gas, for which an equation is derived on the basis of the Nernst heat theorem. If it is assumed that the specific heat of free electrons in the metal is negligible while the specific heat of the evaporated electrons is the same as that of a monatomic gas, the equation assumes the simple form I=AT2ε-b0 / T, where b0=ϕ0e / k (e is electronic charge, k is the Boltzmann constant, and ϕ0=ϕ-3 / 2kT / e, where ϕ is the Richardson work function). An equation of this form has been suggested before but not on the same theoretical grounds and a different value of A has been obtained. Its chief advantage over the usual Richardson equation, I=A1T1 / 2ε-b / T, where b=ϕe / k, is that A is theoretically a universal constant. (2) The value of the universal emission constant A is computed in two ways. Using the Sackur-Tetrode equation for the chemical constant i0, A comes out 60.2 amp./cm2 deg.2, while the theory of rational units of Lewis, Gibson and Latimer gives 50.2 amp./cm2 deg.2. Recent experimental results of Davisson and Germer, and of Schlichter as well as data obtained by the writer agree with the new equation as well or better than with the old, but the temperature scale is not sufficiently accurately known to distinguish experimentally between the two values of A. (3) The relation between A and the chemical constant i0 (or C0) is derived. Values of the work function in equivalent volts have been computed from the experimentally determined values of b0, for tungsten (4.53), thorium (2.94), molybdenum (4.31), tantalum (4.40), and calcium (2.24) within ½ to 1 per cent. The values for uranium (3.28), zirconium (3.28), yttrium (3.19) and cerium (3.07) are upper limits. In general, the values are lower the larger the atomic volumes. Experimental details will be given later.}, added-at = {2007-08-06T19:23:13.000+0200}, author = {Dushman, Saul}, biburl = {https://www.bibsonomy.org/bibtex/2e659d8f5b022d89e25cd5b05092a1712/essential.beatfinger}, description = {Phys. Rev. 21 (1923): Saul Dushman - Electron Emission from Metals...}, doi = {10.1103/PhysRev.21.623}, interhash = {40f90b98dba3d44e58d035a410b89cc4}, intrahash = {e659d8f5b022d89e25cd5b05092a1712}, journal = {Phys. Rev.}, keywords = {imported physics science thermionic thermionicemission thesis}, month = Jun, number = 6, numpages = {13}, pages = {623--636}, publisher = {American Physical Society}, timestamp = {2007-08-06T19:23:13.000+0200}, title = {Electron Emission from Metals as a Function of Temperature}, url = {http://link.aps.org/abstract/PR/v21/p623}, volume = 21, year = 1923 }