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We investigated the adsorption processes of terphenyl (TP) derivatized thiols, [1,1‘:4‘,1‘ ‘-terphenyl]-4-thiol (TP0), which form self-assembled monolayers (SAMs) on Au(111). Scanning tunneling microscopy observation revealed that the adsorption process is dependent on the solvent in which the TP0 molecules can dissolve. When methylene chloride was used as a solvent, the TP0 molecules nucleate anisotropically along 〈112〉 directions with a 3-fold symmetry at the initial stage. At 1 min of immersion, a phase-separated image was taken. In the topographically lower region, molecular lattices (a = 0.65 ± 0.05 nm, b = 1.3 ± 0.05 nm) appeared, where the TP0 molecules were arranged parallel to the Au surface. After more than 5 min of immersion, the molecular lattices disappeared and larger striped patterns with a spacing of ca. 8 nm were observed. On the other hand, when ethanol was used as a solvent, the adsorption process of the TP0 molecules completely changed, and such larger striped patterns were not observed after 1 day of immersion. Our data demonstrate that ethanol facilitated the formation of the more densely packed TP0 SAMs than methylene chloride solvent.

The construction and use of a dual radiator Ring Imaging Cherenkov (RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasises measurements of semi-inclusive deep-inelastic scattering. It provides particle identification for pions, kaons, and protons in the momentum range from 2 to 15 GeV, which is essential to these studies. The instrument uses two radiators, C4F10, a heavy fluorocarbon gas, and a wall of silica aerogel tiles. The use of aerogel in a RICH detector has only recently become possible with the development of clear, large, homogeneous and hydrophobic aerogel. A lightweight mirror was constructed using a newly perfected technique to make resin-coated carbon-fiber surfaces of optical quality. The photon detector consists of 1934 photomultiplier tubes (PMT) for each detector half, held in a soft steel matrix to provide shielding against the residual field of the main spectrometer magnet. (C) 2002 Elsevier Science B.V. All rights reserved

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