Acceptor impurities hydrogen effects

The variations in D and D and the much larger value for In show the limitations of a simple hydrogen atom model. Other elements, particularly transition metals, tend to introduce several deep levels in the energy gap. For example, gold introduces a donor level 0.54 eV below D and an acceptor level 0.35 eV above D in siHcon. Because such impurities are effective aids to the recombination of electrons and holes, they limit carrier lifetime. 

The same authors (41) working with specimens of silica gel observed a positive photocatalytic effect in the course of the hydrogen-deuterium exchange reaction. In this case the introduction of an acceptor impurity into a catalyst enhanced the action of irradiation. 

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