| Numéro |
J. Phys. Colloques
Volume 47, Numéro C7, Novembre 1986
33rd International Field Emission Symposium / 33ème Symposium International d'Emission de Champ
|
|
|---|---|---|
| Page(s) | C7-111 - C7-115 | |
| DOI | https://doi.org/10.1051/jphyscol:1986720 | |
J. Phys. Colloques 47 (1986) C7-111-C7-115
DOI: 10.1051/jphyscol:1986720
FIELD-EMISSION STUDIES OF THE ADSORPTION OF MERCURY ON TUNGSTEN AT 295 K
J.M. SALEHDepartment of Chemistry, College of Science, University of Baghdad, Baghdad, Jadiriya, Republic of Iraq
Abstract
The interaction of mercury vapeur with tungsten has been studied by field-emission microscopy. Adserption of mercury at 295 K occurred on (111) planes and on regions surrounding (001), (112) and (011) planes. The adserption at a pressure of 10-6 N m-2 was complete within 2 minutes. An increase in the average work function of 0.182 volt has been estimated for the process. On heating a surface saturated with mercury at 295 K, surface migration began at temperatures > 750 K to and over the central (011) planes along the zones linking it with the other (011) planes ; the activation energy (E) of the process was 45-50 k J mol-1. Desorption of the absorbed mercury started above 1200 K and the values of E for surface migration and desorption increased with temperature attaining a constant value of 120 k J mol-1 at temperatures > 1700 K. The surface potential changes throughout adsorption, surface migration and desorption have been determined.