- Access by Xinjiang University
Adsorption of Thorium on Tantalum
Phys. Rev. 65, 46 – Published 1 January, 1944
DOI: https://doi.org/10.1103/PhysRev.65.46
Abstract
It is known that thorium adsorbed on the surface of tungsten or molybdenum results in a decrease in the work function and also a decrease in the value of , the emission constant. The behavior of thorium on tantalum was investigated, and similar effects were noted. Thorium was evaporated from thoriated tungsten onto a well-outgassed tantalum ribbon, and the thermionic emission at 1390°K was studied as a function of the time of evaporation. The work function of the ribbon changed from 4.07 volts to 2.52 volts, while decreased by a factor of thirty. The ribbon was then held at 1550°K, and the emission from the two sides was studied separately. The emission from the activated side decreased, while that of the clean side increased until both reached the same final level after about twenty hours. This indicates that the adsorbed thorium had migrated around the edges of the ribbon and distributed itself uniformly over the emitting surface.
References (9)
- A. L. Reimann, Thermionic Emission (John Wiley & Sons, 1934), pp. 99, 134
- W. H. Brattain and J. A. Becker, Phys. Rev. 43, 428 (1933)
- E. Brüche and H. Mahl, Zeits. f. tech. Physik, No. 12, 623 (1935) ibid.No. 8, 262 (1936)
- M. Benjamin and R. O. Jenkins, Proc. Roy. Soc. A176, 262 (1940) ibid.A180, 225 (1942)
- A. J. Ahearn and J. A. Becker, Phys. Rev. 54, 448 (1938)
- L. Malter and D. Langmuir, Phys. Rev. 55, 743 (1939)
- S. Dushman, H. N. Rowe, J. Ewald, and C. A. Kidner, Phys. Rev. 25, 338 (1925)
- E. A. Coomes, Phys. Rev. 55, 519 (1939)
- J. A. Daniel, Phys. Rev. 61, 657 (1942)