Modifications of Fullerenes Extractions and Chromatographies with Different Solvents

In the Bucky System II, based on electrical arc method, carbon soot was produced. Fullerenes C₆₀ and C₇₀ were Soxhlet extracted from the collected soot samples with toluene, chlorobenzene and with both of them successively, modifying the original methods. The yields of the both obtained toluene extracts were 5.4%. Chlorobenzene extract yield was 5.8%. After extraction of toluene insoluble soot with chlorobenzene, the entire extract yield was increased from 5.4% to 5.8%, due to modification of the existing methods. The difference of fullerenes solubilities in these solvents has been concluded. In the second part of our work toluene and chlorobenzene fullerenes extracts were separated by column chromatographies on active Al₂O₃, modifying the existing methods, by elution with hexane and mixtures of benzene, toluene, or xylene with hexane in determined ratios and orders. Identifications of buckminsterfullerene C₆₀ in the first chromatographically purified fractions were achieved by electron impact ionization (EI) mass, IR, and UV/VIS spectroscopy. The second and the third purified fullerene fractions, toluene and chlorobenzene soot extracts were characterized by IR and UV/VIS methods.     

Development of UV/VIS spectrometric methodology for corrosion inhibitor residuals monitoring in oilfield brine

This work focuses on the development of UV/VIS spectrometric methodology for corrosion inhibitor residuals monitoring in oilfield brine. There is no standard method for the determination of corrosion inhibitor concentration in oilfield brine. Developed methodology can be described as a rugged and simple alternative to the sophisticate separation techniques and can be easily applied in the field. The applicability of the method is demonstrated by the analyses of three commercial products. The extensive performance characteristics test, in combination with study and quantification of measurement uncertainty, shows that developed method meets all required criteria and can be directly applied for routine monitoring purposes within quality management system conditions. Therefore, this new method was accredited by the respectable accreditation agency. Valid and reliable determination of corrosion inhibitor residuals in oilfield brine is important in order to ensure effective corrosion protection of metal construction.     

Polymorphism of Phosphine‐Protected Gold Nanoclusters: Synthesis and Characterization of a New 22‐Gold‐Atom Cluster

A new Au₂₂ nanocluster, protected by bis(2‐diphenyl‐phosphino)ethyl ether (dppee or C₂₈H₂₈OP₂) ligand, has been synthsized and purified with high yield. Electrospray mass spectrometry shows that the new cluster has a formula of Au₂₂(dppee)₇, containing 22 gold atoms and seven dppee ligands. The cluster is found to be stable as a solid, but metastable in solution. The new cluster has been characterized by UV‐Vis‐NIR absorption spectroscopy, collision‐induced dissociation, and ³¹P‐NMR. The properties of the new cluster have been compared with the previous Au₂₂(dppo)₆ nanocluster (dppo = 1,8‐bis(diphenyl‐phosphino)octane or C₃₂H₃₆P₂), which contains two fused Au₁₁ units. All the experimental data indicate that the new Au₂₂(dppee)₇ cluster is different from the previously known Au₂₂(dppo)₆ cluster and represents a new Au₂₂ core, which contains most likely one Au₁₁ motif with several Au₂(dppee) or Au(dppee) units. The Au₂₂(dppee)₇ cluster provides a new example of the ligand effects on the nuclearity and structural polymorphism of phosphine‐protected atom‐precise gold nanoclusters.     

Optical and electrical properties of 2 wt.% Al2O3-doped ZnO films and characteristics of Al-doped ZnO thin-film transistors with ultra-thin gate insulators

Al-doped ZnO (AZO) thin films have been prepared on the c-Si oriented direction of (100) and glass substrates, by radio frequency magnetron sputtering from ZnO-2 wt.% Al₂O₃ ceramic targets. The effects of the working pressure on the optical and electrical properties of the films have been studied. The optical properties, measured by the ultraviolet-visible system, show that the transmittance and optical bandgap energy are influenced by the working pressure. The Hall resistivity, mobility, and carrier concentration were obtained by a Hall measurement system and these parameters were also influenced by the working pressure. The AZO thin-film transistors (TFTs) were fabricated on highly doped c-Si substrates. The TFT structures were made up AZO as the active layer and SiO_xN_y/SiN_x/SiO_x as the gate layer with 20 nm and 35 nm thickness, respectively. The ultra-thin TFTs had an on/off current ratio of 10⁴ and a field-effect mobility of 0.17 cm²/V·s. These results show that it is possible to fabricate an AZO TFT that can be operated with an ultra-thin gate dielectric.