Growth of nanocrystalline MoO{sub 3} on Au(111) studied by in situ scanning tunneling microscopy
- Department of Chemistry, Harvard University, Cambridge, Massachusetts 02138 (United States)
The growth of nanocrystalline MoO{sub 3} islands on Au(111) using physical vapor deposition of Mo has been studied by scanning tunneling microscopy and low energy electron diffraction. The growth conditions affect the shape and distribution of the MoO{sub 3} nanostructures, providing a means of preparing materials with different percentages of edge sites that may have different chemical and physical properties than atoms in the interior of the nanostructures. MoO{sub 3} islands were prepared by physical vapor deposition of Mo and subsequent oxidation by NO{sub 2} exposure at temperatures between 450 K and 600 K. They exhibit a crystalline structure with a c(4x2) periodicity relative to unreconstructed Au(111). While the atomic-scale structure is identical to that of MoO{sub 3} islands prepared by chemical vapor deposition, we demonstrate that the distribution of MoO{sub 3} islands on the Au(111) surface reflects the distribution of Mo clusters prior to oxidation although the growth of MoO{sub 3} involves long-range mass transport via volatile MoO{sub 3} precursor species. The island morphology is kinetically controlled at 450 K, whereas an equilibrium shape is approached at higher preparation temperatures or after prolonged annealing at the elevated temperature. Mo deposition at or above 525 K leads to the formation of a Mo-Au surface alloy as indicated by the observation of embedded MoO{sub 3} islands after oxidation by NO{sub 2}. Au vacancy islands, formed when Mo and Au dealloy to produce vacancies, are observed for these growth conditions.
- OSTI ID:
- 20658141
- Journal Information:
- Journal of Chemical Physics, Vol. 121, Issue 23; Other Information: DOI: 10.1063/1.1808422; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANNEALING
ATOMIC CLUSTERS
CHEMICAL VAPOR DEPOSITION
CRYSTAL GROWTH
ELECTRON DIFFRACTION
GOLD
GOLD ALLOYS
MOLYBDENUM ALLOYS
MOLYBDENUM OXIDES
NANOSTRUCTURES
NITROGEN DIOXIDE
OXIDATION
PHYSICAL PROPERTIES
PHYSICAL VAPOR DEPOSITION
SCANNING TUNNELING MICROSCOPY
VACANCIES