Papers by Keyword: Atomic Force Microscope (AFM)

Abstract: Photoacid generators (PAGs) have been widely used as a key component in a chemically amplified photoresist system. The PAG monomer containing an arylsulfonium triflate group was synthesized and was polymerized with benzyl methacrylates. The molecular weight and the content of PAG were controlled to improve thermal stability and sensitivity for atomic force microscope lithography. The fabrication of anodization patterns, which can be enhanced by addition of PAG unit to resist, was achieved at the low bias voltage and the high speed of AFM patterning. The physical properties of resists and lithographic factors affecting the high speed AFM lithography will be discussed.

Abstract: We report on the distribution of mixed self-assembled monolayers (SAMs) composed of biotinylated and diluent alkylthiolates for streptavidin immobilization. Two thiol derivatives, 11-mercapto-1-undecanol (MUOH) and 11-mercaptoundecanoic-(8-biotinylamido-3,6-dioxaoctyl) amide (MBDA), were employed for mixed SAM. These thiols formed self-assembled monolayer without local domain, and streptavidins were immobilized onto biotinylated gold surface without nonspecific binding. In order to find the optimized condition of immobilization of streptavidin, we controlled the mixing ratio of two kind thiols by colorimetric detection assay, and the immobilization was characterized by atomic force microscopy (AFM), scanning tunneling microscopy (STM), and ellipsometer.

Abstract: In this paper, the corrosion phenomenon occurred on the polycrystalline gold substrates has been for the first time observed by in situ quartz crystal microbalance (QCM) method for adsorption of alkanethiol monolayers, which may be attributed to thiol-induced dissolution of gold during the adsorption process in the presence of oxygen. It is evident from the image of many corrosive defects or holes produced on the surface of gold grains by using atomic force microscopy (AFM). The kinetic equation on corrosion rate of gold dissolved in the organothiol solution has been obtained. The gold corrosion rate at fast stage can be estimated to be 9.2 × 1011 Au atoms cm-2 s-1.

Abstract: Behaviors of fracture and deformation in a Zr-Al-Ni-Cu bulk metallic glass(BMG) was investigated by using three-point bending tests. Apparent fracture toughness obtained by bending test was 40MPam1/2 which is comparable to the value of ductile crystalline metals. This high toughness of the BMG should be understood by the crack-tip plasticity as well as crystalline metals. It is well known that plastic deformation occurs very inhomogeneously when BMGs are deformed at room temperature. Such inhomogeneity is manifested by the appearance of surface steps caused by localized shear deformation. In the present study, the surface steps due to the localized shear bands near a fracture surface have been examined in detail by using SEM and AFM, where much attention has been paid on the variation of the surface step height measured along the localized shear band. The variation of the step height indicates the gradient of plastic shear deformation, and it can be understood, in principle, as the introduction of elastic singularities corresponding dislocations in the case of crystalline materials.

Abstract: Young’s modulus of nanohoneycomb structures in the vertical direction relative to the pore (generally along the beam length) is measured according to the porosity from bending tests in atomic force microscopy (AFM). The pore diameters of the nanohoneycomb structures are from about 30 to 60 nm. To determine the Young’s modulus of the nanohoneycomb structures, the area moment of inertia of the nanohoneycomb structure is determined according to the arrangement of the pores. The area moment of inertia of the nanohoneycomb structure is found to be affected by the porosity of the nanohoneycomb structures. The Young’s modulus of the nanohoneycomb structures decreases as a function of the porosity in a large range.

Abstract: Amorphous SiC coatings were deposited by RF magnetron sputtering from a sintered SiC target onto Si(100) substrate at room temperature. The influence of RF power on the surface morphology and the RMS surface roughness of the resulting SiC coatings was studied by using atomic force microscopy. Two types of surface morphologies were obtained. The corresponding forming mechanisms were also discussed.

Abstract: Radical reduction of sulphur content in diesel fuel from the mid 90’s had disastrous impact on diesel fuel’s lubricity. Due to the desulphurization process the lubricity of diesel fuel dropped significantly and got crucial nowadays. The lubricity performance of the diesel fuel is evaluated by the HFRR test in Europe. The HFRR value is determined by measuring the equivalent wear scar diameter occurred on the steel ball specimen during the test. The topographies of these wear scars were investigated by AFM and correlation between the morphology of the worn surfaces and the different HFRR values has been found.

Abstract: Langmuir-Blodgett films (LB) of hydroxamic amphiphiles were used as coating barriers on metal surface against corrosion. Two long-chain hydroxamic acids [CH3(CH2)16CONHOH] monolayers in the presence of some divalent cations (Ca2+, Mg2+, and Cu2+) have been studied at different pH of the subphase. The monolayer was characterized by surface pressure-area isotherms and visualized by Brewster angle microscope (BAM). Compact Langmuir layers were deposited on copper surface, where the modified surfaces were characterized by contact angle measurement as well as by electrochemical techniques. The morphology of LB coated copper surface was visualized by atomic force microscopy (AFM). The coated copper surfaces were tested in corrosive media at acidic and neutral pH. The results show that the multi-molecular LB films of hydroxamic acid salts form good barriers against copper corrosion. The comparison of these results with copper coated by LB layers without divalent cations shows that the presence of divalent cations in the subphase increases the copper corrosion inhibition. The octadecanoyl hydroxamic acid (C18N) results in better and more stable monolayer with cations in the subphase.