Accession Number : ADA266138
Title : Real-Space Formation and Dissipation Dynamics of Hexagonal Reconstruction on Au(100) in Aqueous Media as Explored by Potentiodynamic Scanning Tunneling Microscopy
Descriptive Note : Technical rept.
Corporate Author : PURDUE UNIV LAFAYETTE IN DEPT OF CHEMISTRY
Personal Author(s) : Gao, Xiaoping ; Edens, Gregory J ; Hamelin, Antoinette ; Weaver, Michael J
Report Date : Apr 1993
Pagination or Media Count : 48
Abstract : The electrode potential-induced formation and dissipation dynamics of the hexagonal ('hex') reconstruction on ordered Au(100) in perchloric and sulfuric acid electrolytes has been studied by means of in-situ scanning tunneling microscopy (STM). The real-space/real-time evolution of surface structures associated with the potential-dependent hex left and right arrows (1 x 1) phase transition was examined on timescales down to ca 1 s by acquiring STM images during appropriate potential sweeps and steps (dubbed here 'potentiodynamic STM'). Extensive hex domains can be formed by slow cooling following flame annealing and/or by holding the potential at values significantly below the potential of zero charge for the (1 x 1) surface. The sharp removal of the reconstruction seen voltammetrically, during positive-going potential sweeps, is accompanied by rapid ( 1 s) formation of arrays of ordered (1 x 1) clusters, created from the release of the ca 24% additional gold atoms utilized in the (5 x 27) and related hex structures compared with the (1 x 1) substrate. These clusters are significantly, twofold, larger (ca 4-6 nm) when formed in sulfuric acid electrolyte, due probably to an enhanced surface mobility in the presence of adsorbed sulfate.
Descriptors : *SCANNING , *DYNAMICS , *DISSIPATION , *GOLD , *TUNNELING , *MICROSCOPY , METALS , ANNEALING , INTERFACES , ADSORPTION , VACUUM , SUBSTRATES , ELECTROLYTES , FLAMES , TRANSITIONS , RELEASE , IMAGES , ELECTRODES , SURFACES , COOLING , ATOMS , PERCHLORIC ACID , ATOMIC STRUCTURE , SULFURIC ACID , ACIDS , VOLTAMMETRY , SULFATES , ELECTROCHEMISTRY , ARRAYS , STRUCTURES , PHASE TRANSFORMATIONS , MOBILITY , REMOVAL , REAL TIME
Subject Categories : Inorganic Chemistry
Atomic and Molecular Physics and Spectroscopy
Distribution Statement : APPROVED FOR PUBLIC RELEASE