Journal of Physical Chemistry B, Vol.102, No.15, 2677-2683, 1998
In situ optical second harmonic rotational anisotropy measurements of an Au(111) electrode during electrochemical deposition of tellurium
The electrodeposition of Te on a single-crystalline Au(111) electrode was studied with 1064-nm-excited SH rotational anisotropy measurements. The SH rotational anisotropy was significantly changed with the first underpotential deposition (upd) of Te, and the bulk Te deposition attenuated the anisotropic character of the overall surface symmetry. The change in the SH rotational anisotropy during the first upd of Te was examined using two different models. The first model considered only the contribution of the Au(111) surface to the SHG response, while the second one took into account the contributions of both the Au(111) substrate and the adsorbed Te layer. In the former case, the change in the SH rotational anisotropy can be explained by considering the quenching of the nonlinear susceptibility of the Au(111) surface. The analysis based on the latter model resulted in a rotation angle of 608 for the adsorbed Te layer against the the Au(111) lattice. This value was not consistent with that expected from the adsorbate structure of the first upd layer of Te, i.e., (root 3x root 3)R30 degrees. Thus. the former model seems to be more appropriate to explain the present results. The SH rotational anisotropy measurement also suggests that the morphology became more isotropic after the bulk Te deposition.
Keywords:ATOMIC LAYER EPITAXY;SURFACE 2ND-HARMONIC GENERATION;SCANNING-TUNNELING-MICROSCOPY;LOW-INDEX PLANES;UNDERPOTENTIAL DEPOSITION;ALTERNATED ELECTRODEPOSITION;PHASE MEASUREMENTS;GOLD ELECTRODES;GAAS DEPOSITION;GLASSY-CARBON