Spin-polarized surface electronic states in Ni͑111͒ have been examined using scanning tunneling microscopy ͑STM͒ and spectroscopy ͑STS͒ combined with high-resolution angle-resolved photoemission spectroscopy ͑HR-ARPES͒. Standing waves derived from the majority-spin Shockley surface state ͑SS͒ have been observed in the STM and dI / dV images. The fast Fourier transform ͑FFT͒-dI / dV image at a different sample bias exhibited a circular contour in the reciprocal space. The radius of the FFT-dI / dV image was in agreement with that of the corresponding constant-energy contour given by the HR-ARPES. The majority-spin Shockley SS is partially occupied and disperses upward, crossing the Fermi level ͑E F ͒ at a wave number of k F = 0.081Ϯ 0.005 Å −1 . The effective mass ͑m ‫ء‬ ͒ with respect to the free-electron mass ͑m e ͒ of the majority-spin Shockley SS was evaluated to be m ‫ء‬ / m e = 0.19Ϯ 0.03. The STS spectrum indicated a pair of the Shockley SS below and above E F with an exchange splitting of ϳ190 meV. By the line-shape analyses of the HR-ARPES spectrum, the lifetime broadening at the ⌫ point was calculated to be 53.6 meV, which agrees well with the width ͑49 meV͒ of the steplike structure in the STS spectrum. The results from the STM/STS and HR-ARPES experiments were found to be mutually consistent.

We have done scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS) as well as current imaging tunneling spectroscopy (CITS) of an Al nanocluster periodic array of a submonolayer-Al/Si(111) system. To understand the formation mechanism of this system in detail, a phase diagram of the Al/Si(111) has been carefully produced. Among several structural phases, the nanocluster phase appears for the deposition thickness of 0.24-0.5 ML at a substrate temperature of 550• C. It has been confirmed that these growth conditions should be carefully chosen to produce the well-defined nanocluster. The site-resolved STS spectra of Al nanocluster at 78 K show an insulating energy gap of 3.3 eV. In the CITS images, we have found different features of space-resolved tunneling current for the filled and empty states, which markedly depend on atomic sites and also on inequivalent half-unit cells.