Momentum-resolved direct and inverse photoemission spectra of the K͞Si͑111͒-͑ p 3 3 p 3 ͒R30 ±-B interface reveals the presence of strongly localized surface states. The K overlayer remains nonmetallic up to the saturation coverage. This system most likely presents the first experimental realization of a frustrated spin 1͞2 Heisenberg antiferromagnet on a two-dimensional triangular lattice. [S0031-9007(97)02423-X]

A saturation surface photovoltage is found to occur during ultraviolet photoemission at low temperatures ( r~ 20 K) on a variety of silicon (HI) surfaces. Below -50 K surface recombination becomes ineffective thereby allowing flat-band conditions to be achieved with mild uv irradiation. Temperature-dependent photoemission thereby provides a simple and direct method for determining band bending and barrier heights. Results for different silicon (111) surfaces and preparation conditions are discussed.

A series of monolithic poly[methyl methacrylate-co-3-(trimethoxysilyl)propyl methacrylate]−silica hybrid materials have been prepared via the sol−gel reactions. The fracture surfaces of the materials were systematically examined with atomic force microscopy (AFM) as a function of the silica content from ∼23 to 100 vol %. For the transparent materials, the AFM image of the sample at a low silica content of 23 vol % is very smooth and essentially featureless while those at higher silica contents show relatively greater surface roughness and development of domains of various shapes and sizes. In sharp contrast, the optically translucent and phase-separated samples exhibit significantly higher surface roughness and larger domain size than all the transparent hybrid materials, suggesting that the transparent materials might have little or no organic−inorganic phase separation.