Surface hydration and its effect on fluorinated SAM formation on SiO2 surfaces

Substrate hydration is demonstrated to be crucial to film quality during self-assembled (SA) film deposition of tridecafluoro-1,1,2,2,-tetrahydrooctyltrichlorosilane (FOTS) from the vapor phase. The surface hydration was studied by thermogravimetric analysis, and a model was developed to predict the conditions necessary to desorb all of the water adsorbed on a fused silica surface without significantly altering the concentration of the surface hydroxyl groups. The nature of the SA film was investigated as a function of the degree of rehydration of the dehydrated silica surface. The wettability and microstructure of the SA films were examined by water contact angle, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. There is an optimum degree of substrate hydration, on the order of 1-1.2 monolayers of adsorbed water, required to produce a dense, durable and uniform FOTS film with high water repellency and a smooth surface.     

Experimental and theoretical investigation on surfactant segregation in imprint lithography

The effects of template surface composition on fluorinated surfactant segregation were investigated for imprint lithography with photopolymerizable vinyl ether formulations. Heptadecafluoro-1,1,2,2-tetrahydrodecyl vinyloxy-methyloxy dimethylsilane, containing a vinyl ether group, was employed as the surfactant, and blanket templates were pressed onto the liquid and illuminated with UV radiation from below. The extent of surfactant segregation to the vinyl ether-template interface before polymerization was characterized using contact angle measurements and angle-resolved X-ray photoelectron spectroscopy after removing the template from the cured vinyl ether polymer. Blanket surfaces consisting of bare quartz, high-density polyethylene, and quartz treated with tridecafluoro-1,1,2,2,-tetrahydrooctyltrichlorosilane afforded templates with different surface energy and polarity. The highest degree of surfactant segregation was found with tridecafluoro-1,1,2,2,-tetrahydrooctyltrichlorosilane-treated quartz, whereas little surfactant segregation was found for bare quartz. A thermodynamic model is developed to predict the surface segregation profiles.     

Catalytic degradation of lignin model compounds in acidic imidazolium based ionic liquids: Hammett acidity and anion effects

Ionic liquids based on the 1-methylimidazolium cation with chloride, bromide, hydrogen sulfate, and tetrafluoroborate counterions along with 1-butyl-3-methylimidazolium hydrogen sulfate were employed to degrade two lignin model compounds, guaiacylglycerol-β-guaiacyl ether and veratrylglycerol-β-guaiacyl ether. The acidity of each ionic liquid was approximated using 3-nitroaniline as an indicator to measure the Hammett acidity (H₀). While all of the tested ionic liquids were strongly acidic (H₀ between 1.48 and 2.08), the relative acidity did not correlate with the ability of the ionic liquid to catalyze β-O-4 ether bond hydrolysis. The reactivity of the model compounds in the ionic liquids is dependent not only on the acidity, but also on the nature of the ions and their interaction with the model compounds.     

A two-sided Arnoldi algorithm with stopping criterion and MIMO selection procedure

In this paper we introduce a two-sided Arnoldi method for the reduction of high order linear systems and we propose useful extensions, first of all a stopping criterion to find a suitable order for the reduced model and secondly, a selection procedure to significantly improve the performance in the multi-input multi-output (MIMO) case. One application is in micro-electro-mechanical systems (MEMS). We consider a thermo-electric micro thruster model, and a comparison between the commonly used Arnoldi algorithm and the two-sided Arnoldi is performed.     

Interaction of germanium with silicon dioxide

The interaction of germanium (Ge) adatoms with SiO₂ (silica) plays an important role in selective, heteroepitaxial growth of Ge(100) through windows created in silica on Si(100) and in the selective growth of Ge nanoparticles on hafnia, located at the bottom of pores etched through silica. Both processes rely on the inability of Ge to accumulate on silica. In hot wire chemical vapor deposition of Ge nanoparticles from GeH₄, etching of the silica has been invoked as one path to prevent accumulation of Ge on silica; whereas dense silica is not etched when Ge atoms are incident on the surface in molecular beam processes. Surface studies were conducted to determine the nature of oxidized Ge on SiO₂, to reconcile the etching claim with GeH₄, and to look for the additional etching product that must accompany GeO, namely SiO. Etching of silica is not found with GeH₄ or GeH_x fragments. A more complete examination of the Ge isotopes reveals instead the m/e 90 signal, previously attributed to GeO, originates from interactions between iron oxide impurities in the molybdenum holder, and hydrogen and GeH_x fragments. Coating the Mo with gold eliminates m/e 90 from Ge TPD spectra. The high temperature m/e 74 and m/e 2 peaks observed from 800 to 900 K are attributed to GeH_x decomposition to Ge and H followed by their desorption, while the appearance of GeO_x is attributed to possible reactions between GeH_x species with hydroxyl groups and/or oxidation of Ge clusters by background oxidants.     

Working group report: Heavy-ion physics and quark-gluon plasma

This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported.