Benchmark measurements of the ionization balance of non-local-thermodynamic-equilibrium gold plasmas

We present a series of benchmark measurements of the ionization balance of well-characterized gold plasmas with and without external radiation fields at electron densities near 10{21} cm{-3} and electron temperatures spanning the range 0.8 to 2.4 keV. We have analyzed time- and space-resolved M-shell gold emission spectra using a sophisticated collisional-radiative model with hybrid level structure, finding average ion charges Z ranging from 42 to 50. At the lower temperatures, the spectra exhibit significant sensitivity to external radiation fields and include emission features from complex N-shell ions. The measured spectra and inferred Z provide a stringent test for non-local-thermodynamic-equilibrium models of complex high-Z ions.     

Chemical functionalization of diamond surfaces by reaction with diaryl carbenes

A rapid route to the chemical functionalization of hydrogen-terminated diamond surfaces deposited by chemical vapor deposition involving their reaction with substituted diaryl carbenes has been investigated. To avoid difficulties in the handling of highly reactive compounds, the carbene is generated in situ from the thermal decomposition at 400 K of a thin film of the corresponding diaryl diazomethane precursor deposited at the diamond interface. X-ray photoelectron spectroscopy (XPS) has been used to verify that surface functionalization using two starting compounds, bis(4-iodophenyl) diazomethane and bis(4-nitrophenyl) diazomethane, can be achieved using this approach in agreement with recent theoretical studies. The surface grafting density is measured to be around 10(14) cm(-2) in each case. The chemistry observed is found to be insensitive to the detailed properties of the diamond film and to the presence of oxygen contamination at the hydrogen-terminated diamond surface. We further demonstrate the utility of the approach, in the case of the bound nitrophenyl compound, by its reduction to the corresponding primary amine followed by reaction with fluorescein isothiocyanate to achieve fluorescent tagging of the diamond interface.     

Ultra-thin Oxide Films on SiO2: An STM Study of Their Thermal Stability in the Presence of Au Deposit

ＩｎｔｒｏｄｕｃｔｉｏｎＭｅｔａｌ ｏｘｉｄｅ ｓｅｍｉｃｏｎｄｕｃｔｏｒ(ＭＯＳ)ｓｔｒｕｃｔｕｒｅｉｎ ｖｏｌｖｉｎｇａｔｈｉｎｌａｙｅｒｏｆＳｉＯ2 ｓａｎｄｗｉｃｈｅｄｂｅｔｗｅｅｎａＳｉｓｕｂｓｔｒａｔｅａｎｄａｍｅｔａｌｇａｔｅｅｌｅｃｔｒｏｄｅｉｓｏｆｃｒｕｃｉａｌｉｍ ｐｏｒｔａｎｃｅｉｎｆｉｅｌｄｅｆｆｅｃｔｔｒａｎｓｉｓｔｏｒｓ .Ａｔｐｒｅｓｅｎｔ,ｏｘｉｄｅｂａｒｒｉｅｒｌａｙｅｒｓａｓｔｈｉｎａｓ 80 ａｒｅｕｓｅｄｉｎｈｉｇｈｐｅｒｆｏｒ ｍａｎｃｅｓｉｌｉｃｏｎｄｅｖｉｃｅｓ[1]…     

Reaction kinetics for the CBE growth of GaAs from triethylgallium; computer modelling studies incorporating recent surface spectroscopic data

A new model for the decomposition of triethylgallium on GaAs(100), with kinetic parameters derived from the results of surface science experiments, is presented. Deficiencies of early models are corrected by including surface coverage and site blocking effects, and lateral interactions between absorbed DEG species are included. The model successfully predicts variations in the rate of CBE growth of GaAs with substrate temperature, and addresses effects induced by variations in arsenic overpressure. This dependence of growth rate on the arsenic flux is modelled by computing the steady state concentrations of absorbed arsenic as a function of temperature and As₂ and TEG flux. Excess arsenic is shown to inhibit GaAs growth by blocking sites for TEG absorption.     

Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis

Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur.