Surface and Bulk Plasmon Excitation on Aluminum Surface at Small to High Grazing Angles

We present a series of spectra measured by reflected electron energy loss spectroscopy on an aluminum sample using a cylindrical mirror analyzer. The measurements were performed in the energy range between 250 eV and 2000 eV and with various incident angles, including the grazing geometry of an 88° incident angle. The observed spectra were evaluated and decomposed for surface and bulk excitation. The determined surface plasmon excitations were compared to the elastic peak and to the bulk excitation. We found a slight surface plasmon energy shift with altering glancing angles. We show that this shift exists independently from the bulk plasmon interference

A versatile characterization of poly(N-isopropylacrylamideco- N,N'-methylene-bis-acrylamide) hydrogels for composition, mechanical strength, and rheology

Poly(N-isopropylacrylamide-co-N,N"-methylene-bisacrylamide) (P(NIPAAm-co-MBA)) hydrogels were prepared in water using redox initiator. The copolymer composition at high conversion (> 95%) was determined indirectly by HPLC (high performance liquid chromatography) analysis of the leaching water and directly by solid state 13C CP MAS NMR (cross polarization magic angle spinning nuclear magnetic resonance) spectroscopy of the dried gels, and was found to be close to that of the feed. The effect of cross-linker (MBA) content in the copolymer was investigated in the concentration range of 1.1–9.1 mol% (R:90–10; R = mol NIPAAm/mol MBA) on the rheological behaviour and mechanical strength of the hydrogels. Both storage and loss modulus decreased with decreasing cross-linker content as revealed by dynamic rheometry. Gels R70 and R90 with very low cross-linker content (1.2–1.5 mol% MBA) have a very loose network structure, which is significantly different from those with higher cross-linker content manifesting in higher difference in storage modulus. The temperature dependence of the damping factor served the most accurate determination of the volume phase transition temperature, which was not affected by the cross-link density in the investigated range of MBA concentration. Gel R10 with highest cross-linker content (9.1 mol% MBA) behaves anomalously due to heterogeneity and the hindered conformation of the side chains of PNIPAAm

The chemical resistance of nano-sized SiC rich composite coating

Abstract 30 keV Ga+ implantation was applied to a nominally C(20 nm)/Si(20 nm)/C(20 nm)/Si(20 nm)/C(20 nm)/Si substrate multilayer system. Due to the irradiation intermixing occurred and a layer containing C, Si, Ga and (amorphous) SiC was obtained. The thickness (7–30 nm) and composition of the layer depended on the fluence of irradiation. The chemical resistance of the layer was tested by applying microwave oxidation and various polysilicon etchants and was found to be excellent if the SiC concentration was above 20%. Using an etchant with an etching rate of about 100 nm/s for poly-Si during 10 s had not affected the integrity of the intermixed region with a thickness of 10 nm; only some defects appeared. With a further increase of the etching time the size of defects increased resulting in inhomogeneous layer removal. The in-depth composition of non-defective region that remained on the surface was determined by AES depth profiling, which revealed that the intermixed layer did not change during the harsh etching except the removal of its thin surface layer containing less than 20% SiC. The etching rate of the intermixed layer is orders of magnitude lower than that for poly-Si

Examination of nanocrystalline TiC/amorphous C deposited thin films

The relationship between structural, chemical and mechanical properties of nanocrystalline TiC / amorphous C thin films was studied. Thin films were deposited by DC magnetron sputtering on oxidized silicon substrates in argon at 25 C° and 0.25 Pa. The input power of the carbon target was 150 W, the input power of the titanium target was varied between 15 and 50 W. It was found that all thin films consist of a few nanosized columnar TiC crystallites embedded in carbon matrix. The average size of TiC crystallites and the thickness of the carbon matrix have been found to correlate with Ti content. The mechanical properties of the films have been strictly dependent on their structure. The highest values of the nanohardness (~ 66 GPa) and Young's modulus (~ 401 GPa) were observed for the film with the highest TiC content which was prepared at 50 W of Ti target

Determination of chlorophyll content in case of peach leaf curl disease (Taphrina deformans) with spectral analysis

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