Web Release Date: December 23,
Inducing and Observing the Abstraction of a Single Hydrogen Atom in Bimolecular
Reactions with a Scanning Tunneling Microscope
Laboratory of Atomic and Solid State Physics and Cornell Center for Materials Research, Cornell University, Ithaca, New York 14853
Received: July 12, 2000
In Final Form: October 19, 2000
Abstract:
A variable-temperature scanning tunneling microscope (STM) was used to initiate and observe the abstraction
of a single hydrogen atom in a simple bimolecular reaction. Dicarbon (CC) on the Cu(001) surface reacted
separately with hydrogen sulfide (H2S) and water (H2O) to form CCH + SH and CCH + OH, respectively.
At 9 K, hydrogen abstraction from H2O occurred spontaneously upon contact between CC and thermally
diffusing H2O molecules. Hydrogen abstraction from H2S was effected at 9 K by inducing H2S diffusion via
excitation with tunneling electrons. The thermal diffusion and reaction of H2S and CC were also observed at
45 K. By removing a single hydrogen atom from H2S and H2O using tunneling electrons, we established the
identities of the sulfhydryl (SH) and hydroxyl (OH) reaction products. SH and OH did not react with CC
under conditions that led to the reaction of the parent molecules. The bimolecular reactions H2O + O 
2OH and H2S + O SH + OH did not occur thermally at 9 K but were induced by tunneling electrons.
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