Tip-Induced Dissociation of Diethyl Ether on Si(001)─Influence of Molecular Structure on Final Reaction Products

Scanning tunneling microscopy gives access to well-controlled manipulation of surface adsorbates by means of activating reaction pathways beyond thermal excitation schemes. For the conversion of diethyl ether on Si(001) from a datively bound intermediate into the covalently bound final state, we show that tip-induced electronic excitation leads to new products when compared to thermal excitation. We emphasize the molecular structure as a key parameter in creating such specific reaction products via electronic excitation by comparing the results for diethyl ether and tetrahydrofuran, the cyclic analogue of diethyl ether. The final configurations of the two systems differ in terms of the reacted surface atoms and their electronic structure; moreover, a new reaction product which indicates the desorption of one of the two molecular fragments induced by tip-induced ether cleavage is dominant in the case of diethyl ether.