Many reactions involving metal-sulfur bonds and oxygen, however, are highly endothermic.
Therefore past explanations of impurity effects have focused on mechanical aspects, such as interfacial roughening. Our work has demonstrated the importance of impurity chemistry at interfaces, and suggests approaches for control and inhibition of such phenomena. Our approach has involved the fabrication of model interfaces under controlled UHV conditions. Therefore free-energy calculations made on the basis of values derived from bulk phases can lead to incorrect predictions. This result is surprising in view of the high dissociation enthalpy for Al-O bonds.