Atomic-Resolution Scanning Tunneling Microscopy and Infrared Spectroscopy as Combined In-Situ Probes of Electrochemical Adlayer Structure: Carbon Monoxide on Rhodium(111)
PURDUE UNIV LAFAYETTE IN DEPT OF CHEMISTRY
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In-situ scanning tunneling microscopy STM has been combined with infrared reflection-absorption spectroscopy IRRAS to yield detailed atomic- level adlayer structures for saturated coverages of CO on ordered Rh111 in aqueous solutions. Two distinctly different structures were obtained in CO- containing 0.1 M NaC104, depending on the electrode potential. At higher potentials, ca -0.1 to 0.3 V vs SCE, atomic-resolution STM images were obtained that indicated the presence of a 2 x 2-3CO unit cell, having a CO coverage in agreement with electrochemical and IRRAS measurements. The corresponding in-situ infrared spectra indicate the presence of two atop or near-atop and one twofold bridging CO in the unit cell. A real-space structure is suggested that is related to the corresponding 2 x 2-3CO adlattice on Rh111 in uhv as deduced previously by low-energy electron diffraction and vibrational spectroscopy.
- Atomic and Molecular Physics and Spectroscopy