| Popis: |
Chemisorption of H, F, Cl, Br and O was studied on the surface of diamond powder. Analyses, heat of wetting, ESR measurements and i.r. spectra are compared. Diamond with chemisorbed oxygen is hydrophilic, whereas diamond covered with hydrogen or halogens is hydrophobic. Diamond outgassed at 950° is hydrophobic, too, although some oxygen is chemisorbed at room temperature. The quantity of free radicals in the surface of diamond after outgassing at 950° is only approximately 1 per cent of the number of “dangling bonds” estimated from the number of surface atoms. Spin concentration and line width decrease on formation of surface compounds. About one third of the surface bonds can be saturated with H, F, or Cl. Complete coverage with O is possible, however. Infrared spectra show the presence of CH2 groups and C-F bonds, respectively. No C-CI absorptions could be detected, however. The surface oxides cause absorptions of carbonyl groups and of ether-type groups. |
