In-situ second-harmonic generation monitoring of Ag deposition onto Si(111)–(√3 x √3)-Ag was conducted at several sample temperatures ranging from −190C to room temperature. The second-harmonic signals from Si(111)–(√21 x √21)-Ag and Si(111)–(6 x 6)-Ag at a photon energy of 1.17eV were identified with the help of low-energy electron diffraction observation. The relatively large second-harmonic signal from Si(111)–(√21 x √21)-Ag was attributed to a resonance related to transitions among surface states. The weak second-harmonic signal observed for Si(111)–(6 x 6)-Ag results from the absence of the metallic surface state band. A 180° phase shift observed for the SinPout signal at about 3ML suggests that an additional Ag deposition onto Si(111)–(6 x 6)-Ag at −190C formed a surface Ag layer in a quasi-layer–by-layer mode.

Reconstruction and Dynamics of Ag Atoms on Si(111)–√3 x √3-Ag Surface Studied by Optical Second-Harmonic Generation. D.Deng, Y.Karaki, T.Suzuki: Surface Science, 2006, 600[15], 3052-7