The Mossbauer effect of FE57 on the surface of tungsten

The Mossbuaer effect of Fe 57 on the surface of polycrystalline tungsten has been measured over a temperature range of 80 - 5000 K, and at angles of 0° and 60° with respect to the normal. The M8ssbauer spectra consist of three unresolved lines, the middle one agreeing with measured spectra of Fe 57 in the bulk of tungsten, and the outer two being attributed to surface effects. The assymmetry of the surface spectra, the angular dependence of the shape, and the magnitude of the splitting of the two surface lines indicate an electric field gradient at the surface of 2.4 x 10 16 V/cm 2 directed along the normal. An effective Debye temperature of 406 + l2°K is found for the bulk, from a study of the temperature dependence of the intensity of the M8ssbauer absorption. The effective Debye temperature for the surface is 354 + 300K along the normal, and 255 + 300K parallel to the surface. The angular dependence of the total intensity of the two surface lines agrees with a simple theory for an atom bound above the top layer of the host lattice. The isomer shift with respect to iron at 300 0K is .0151 + .0002 cm/sec in the bulk, and ,018 ± .002 cm/sec on the surface. The temperature dependence of the shift was not determined with sufficient accuracy to detect any surface effects on the .second order Doppler shift. Experimental apparatus and computer programs are described.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Burton, John Williams

Contributors dc:contributor

• Frauenfelder, Hans

• Mossbauer effect
• iron
• tungsten
• polycrystalline tungsten
• energy shifts
• quadrupole splitting

Statement dc:rights

• 1965 John Williams Burton

Language dc:language

en

Identifier

2299425

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/23965