金属表面に吸収された酸素の効果

概要

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The charge transfer phenomenon on metal catalyzer has been studied by the field-ion microscope and the field-emission microscope. Tantalum and rhodium-tip after field-evaporation of absorbed oxygen show the bright spots in field-ion image, which correspond to the nearest metal atoms of absorbed oxygen.<BR>On the other hand, when the tip-temperature in field-emission microscope is low and the rearrangement of surface atoms does not occur. oxygen preadsorbed on tungsten, molybdenum and rhenium-tip does not affect the charge transfer from cesium to the tip. The surface state of absorption changes from [Cs-M-O-O= (tip)] at about 0.35 of oxygen coverage to [Cs-O-M-O-O= (tip)] at aboot 0.5 after heating tip at about 750°K.<BR>This indicates that the metal catalyzer is activated when it is exposed in the oxygen gas and heated to high temperature. The absorbed sat face has a great faculty of exchanging the electron with the reacting atoms.
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