Tip-induced β -hydrogen dissociation in an alkyl group bound on Si(001)

Abstract

Atomic-scale chemical modification of surface-adsorbed ethyl groups on Si(001) was induced and studied by means of scanning tunneling microscopy. Tunneling at sample bias >+1.5 V leads to tip-induced C–H cleavage of a β-hydrogen of the covalently bound ethyl configuration. The reaction is characterized by the formation of an additional Si–H and a Si–C bond. The reaction probability shows a linear dependence on the tunneling current at 300 K; the reaction is largely suppressed at 50 K. The observed tip-induced surface reaction at room temperature is thus attributed to a one-electron excitation in combination with thermal activation.

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

“…It is excluded that this configuration evolves from a double-row straight configuration via a hopping event of a molecular fragment along the dimer rows as such an event could not be observed under equal scanning conditions for double-row straight configurations produced via thermal activation. 33,34 The single-row diagonal configuration shown in Figure 2f is again characterized by two saturated Si atoms; however, they are located on two dimers next to each other on the same dimer row. The saturated atoms are arranged in an alternating structure.…”

Chemoselective Adsorption of Allyl Ethers on Si(001): How the Interaction between Two Functional Groups Controls the Reactivity and Final Products of a Surface Reaction

“…For comparison, in Figure 3b, an image of diethyl ether on Si(001) at 50 K is shown. In that case, the W-shaped features, which were attributed to the datively bound intermediate state of the molecules, 37 are observed as well. Thus, in combination with the XPS studies, the features in Figure 3a are assigned to the intact AME molecules datively bound to the Si(001) surface via the oxygen atom of the ether group.…”

Atomic and molecular functionalisation of technological materials: an introduction to nanoscale processes on semiconductor surfaces

“…Chemistry induced with a tip of scanning tunneling microscope is one of the most revered approaches for molecular level manipulation. A paper by Adamkiewicz et al [1] in this special issue makes a clear connection between the physics of addressing an ethyl group that is stable at room temperature with a tip-induced excitation to stimulate a controllable chemical process. This work takes the science of a chemical tip-induced change to the next level by understanding the process as a combination of one-electron excitation and thermal activation.…”