A van der Waals DFT study of chain length dependence of alkanethiol adsorption on Au(111): Physisorption vs.chemisorption

The energetics and structures of physisorbed and chemisorbed alkanethiols on Au(111) have been systematically investigated up to 10 carbon atoms using van der Waals (vdW) corrected density functional theory (DFT) calculations. The role of chain length, tilting angle and coverage on the adsorption characteristics have been examined to elucidate the energetics and plausible transformation mechanisms between lying down and standing up phases. Coverage and size dependent chain-chain electronic interactions counteract with the alkyl chain-gold surface interactions and the surface relaxation of the metal in the formation of standing up monolayer structures. For the striped phases of long chain alkanethiols, however, our calculations on decanethiol indicates alkyl chain-gold surface interactions to be strong enough to force the molecule to be perfectly parallel to the surface by lifting a gold atom up, in agreement with the proposed models for this film in the literature.Comment: 11 pages, 10 figures, 4 table

FEN BİLİMLERİ ENSTİTÜSÜ/LİSANSÜSTÜ TEZ PROJESİ

ESER MADDE TAYİNİ İÇİN FİBER HALKA RİNG-DOWN SPEKTROSKOPİ SİSTEMİ GELİŞTİRİLMES

FEN BİLİMLERİ ENSTİTÜSÜ/LİSANSÜSTÜ TEZ PROJESİ

ESER MADDE TAYİNİ İÇİN FİBER HALKA RİNG-DOWN SPEKTROSKOPİ SİSTEMİ GELİŞTİRİLMES

Simultaneous detection of surface coverage and structure of krypton films on gold by helium atom diffraction and quartz crystal microbalance techniques

We describe a quartz crystal microbalance setup that can be operated at low temperatures in ultra high vacuum with gold electrode surfaces acting as substrate surface for helium diffraction measurements. By simultaneous measurement of helium specular reflection intensity from the electrode surface and resonance frequency shift of the crystal during film adsorption, helium diffraction data can be correlated to film thickness. In addition, effects of interfacial viscosity on the helium diffraction pattern could be observed. To this end, first, flat gold films on AT cut quartz crystals were prepared which yield high enough helium specular reflection intensity. Then the crystals were mounted in the helium diffractometer sample holder and driven by means of a frequency modulation driving setup. Different crystal geometries were tested to obtain the best quality factor and preliminary measurements were performed on Kr films on gold surfaces. While the crystal structure and coverage of krypton films as a function of substrate temperature could successfully be determined, no depinning effects could be observed. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3658819

ESER MALZEME TAYİNİ İÇİN FİBER RİNG-DOWN SEKTROSKOPİ SİSTEMİ GELİŞTİRİLMESİ

ESER MALZEME TAYİNİ İÇİN FİBER RİNG-DOWN SEKTROSKOPİ SİSTEMİ GELİŞTİRİLMES

PFP İNCE FİLMLERİN AFM ÇALIŞMALARI

PFP İNCE FİLMLERİN AFM ÇALIŞMALAR