Abstract
When a layer of oxygen on the (110) plane of tungsten at coverages O/W≦0.5 is heated from 100 K, O+ evolution under electron impact becomes almost negligible at 600 K. On further heating, however, a slow, temperature-dependent evolution of O+ current is observed atT≳1500 K. For O/W>0.3 there is also desorption under massive bombardment. Once an equilibrium value of O+ current has been established, there is rapid adjustment to the appropriate equilibrium value when the temperature changes in the range 1500–1700 K. On cooling toT<1000 K, O+ decreases rapidly; on reheating toT>1500 K, O+ increases slowly again. Above 1700 K there is thermal desorption which is also reflected in the O+ signal. These facts indicate that there is a slow activated evolution of an electron sensitive state above 1500 K, from a reconstructed state formed by heating the low temperature layer toT≧1000 K. The latter state seems to be reformed on cooling below 1500 K.
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Steinbrüchel, C., Gomer, R. Oxygen adsorption on the tungsten (110) plane. Electron impact and thermal desorption at high temperatures. Appl. Phys. 15, 141–148 (1978). https://doi.org/10.1007/BF00928198
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DOI: https://doi.org/10.1007/BF00928198