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The surface morphology of Hg0.8Cd0.2Te epilayers on (111)±0.5° oriented Cd0.96Zn0.04Te substrates grown from Te-rich solution by LPE using horizontal slider has been studied. The surface morphology, apart from exhibiting the terrace patterns typical of LPE growth, shows other surface features like pin holes/voids, Hg-evaporation points, slider scratch marks and some long-distance perturbations in the layer thickness visible to the naked eye. Also, discussed are the surface morphology of the layer at edge regions and the effect of non-smooth slide-out of the layer on its surface morphology. [Copyright &y& Elsevier]

Studies of solid surfaces by slow positron impact have seen notable successes in the last 20 years, and much effort is still concentrated in this area. However, the application of positron diffraction, re-emission or annihilation as a surface probe has yet to become widely established, primarily as a result of the relatively low intensities of high-quality positron beams. This paper reviews the current status of experimental positron-based research on surfaces and considers the prospects for future developments. [Copyright &y& Elsevier]

• Physical properties are obtained from backscattering of ionized projectile fragments. • The surface transition temperature T T (related to the T g) of the polymers is retrieved. • The variation of T T is measured as a function of the thermoset curing. • Surface contamination majorly influence the measured values of backscattered ions. • The breaking ratios are reminiscent of dynamic-mechanical and torsional braid measurements. Surface and thin films are important in modern technologies and there is growing demand for their characterization. Secondary ion mass spectrometry (SIMS) is universally used for extracting information on the chemical composition of surfaces. This study shows that it can provide information about the physical (mechanical) properties of thermoset polymer surfaces. The intensities of backscattered Ar n + clusters were measured upon 10 keV Ar 3000 + gas cluster ion bombardment of polymer films. Tyrosol diaminodiphenylmethane based benzoxazine thermosets with different curing cycles were used. The intensity ratios Ar 2 +/(Ar 2 ++Ar 3 +) and Ar 2 +/(Ar 2 ++Ar 4 +) were highly sensitive to the physical changes of the thermoset coating surfaces as a function of their curing cycle and of temperature. These intensity ratios provide direct access to the surface transition temperature T T (related to the bulk glass transition T g), and show a dependence on the curing degree below and above T T. Moreover, we discuss the influence of surface contamination and clusters induced roughness on the measured values. Our results suggest that contamination has a dramatic influence on the intensity of backscattered Ar n + clusters, while that of roughness appears to be minor. This study constitutes a step forward towards a quantitative assessment of the mechanical properties of polymer coating surfaces using SIMS. [ABSTRACT FROM AUTHOR]

Abstract: Immobilization of protein streptavidin to the surface of polystyrene (PS) polymer was studied by X-ray photoelectron spectroscopy (XPS). Two different protocols were used to attach streptavidin to the PS surface: physical adsorption and chemical coupling. In both cases the surface properties of PS samples were modified by exposure to cold oxygen plasma for 10s. Plasma was created in oxygen at 75Pa by en electrode-less RF discharge. The RF generator operated at 27.12MHz and the nominal power was about 120W. The electron temperature was about 3eV, the plasma density was about 3×1015 m−3 and the neutral oxygen atom density was about 3×1021 m−3. Oxygen plasma treatment caused formation of O-rich functional groups on the surface of PS. The concentration of oxygen was determined by XPS and was about 28at.%. A thin film of streptavidin was deposited by physical adsorption and chemical bonding. The appearance of streptavidin on the surface was determined from XPS spectra measuring the ratio between N and C peaks. The plasma treatment caused poor adsorption and but strong chemisorption of streptavidin. The results were explained by specific interaction of protein with polar functional groups on the surface of PS after plasma treatment. [Copyright &y& Elsevier]

Abstract: We have studied Pb thin films as a function of the thickness up to 60 monolayers (MLs) using ab initio first principles and model calculations. Magic heights corresponding to a modulated oscillatory pattern of the energy of Pb(1 1 1) films have been measured up to about 30 MLs. We demonstrate that this behaviour continues even for higher thickness due to an extra second modulation pattern in the energetics of the metal film as a function of the number of atomic layers. The origin of this second modulation is the nesting of two close values of the Fermi wavelength in the (1 1 1) direction. [Copyright &y& Elsevier]

• Calorimetry of nanogram samples. • Study of heat exchange at the nanoscale. • Calorimetry and surface physics simultaneously on the same support. • Angstrom–level resolution during STM imaging of the thermometer surface. There is a great interest in the scientific community to perform calorimetry on samples having mass in the nanogram range. A detailed knowledge of the energy (heat) exchange in the fast growing family of micro– and nano–systems could provide valuable information about the chemistry and physics at the nano–scale. The possibility to have an atomically flat thermal probe represents an added value, because it provides the unique opportunity to perform Scanning Probe Microscopy (SPM) together with calorimetry. Here we report the fabrication, characterization, and calibration of atomically flat, single–crystalline gold film thermometers on mica substrate. Gold re–crystallization has been obtained, and successively the thermometer surface has been studied by Low Energy Electron Diffraction (LEED) and Scanning Tunneling Microscopy (STM). The thermometer calibration demonstrates a heat exchange coefficient of 2.1 × 10 - 7 W/K and a performance about 10 times better than previous sensors based on Si substrates. The experimental setup allows the simultaneous investigation of heat exchange and surface physics on the same sample. [ABSTRACT FROM AUTHOR]

• Carboxylic acid moieties enhance peel adhesion through the contact with a metallic adherend in a time-dependent manner. • Carboxylic acid moieties are rearranged and exposed to the interface as attached to a metallic adherent. • Chain rearrangement and molecular reorientation trigger the stronger interfacial bonding formation. Although recent literatures have pointed out that viscoelastic dissipation is the main mechanism affecting the adhesion of pressure sensitive adhesives (PSAs), the controversial issue found previously has spurred us to be interested in the contribution of surface chemistry and physics. Herein, it was found that changes in the surface energy of PSAs caused a significant increase in the adhesion energy via rearrangement of the polymer chains, inducing reorientation of the polar group toward the metallic adherend. The adhesion energy increased with increasing contact time on the adherend, where the adhesion performance of acrylic acid-incorporated PSA increased by more than 300% after 24 h contact with stainless steel. The surface energy of the adhesives were calculated as a function of contact time via contact angle measurements and using the Fowkes theory in order to substantiate the changes in the surface properties influencing the adhesion. The surface chemistry of the PSAs was analyzed by Fourier-transform infrared analysis and time-of-flight secondary ion mass spectrometry, which suggest that the enhanced adhesion of acrylic acid-incorporated PSA is due to the contact time-dependent mechanism, in which induces the polymer chains rearranged and polar groups exposed at the interface. [ABSTRACT FROM AUTHOR]