Acidity constants (Ka) of perfluoroalkanoic acids were determined by pH titration and by electric conductivity for shorter alkanoic acids (C1 to C5) with 1 to 5 carbon atoms in the alkyl chain. The acidity constants obtained by the two methods are in good agreement. They increase from C1 (ethanoic) to C3 (butanoic acid) and then decrease from C3 to C5 (hexanoic acid) with increasing alkyl chain length. An abrupt decrease in the Ka value for the C5 acid occurred; the attempt to explain this in terms of viscosity of the solutions did not succeeded. The decrease in the Ka values with increasing alkyl chain length was substantiated by the values for C9 (decanoic) to C11 (dodecanoic) acids, which were determined from the solubility change with the solution pH. For the intermediate alkanoic acids (C6 to C8), the Ka values could not be determined precisely by these methods due to the extreme difficulty in separating the colloidal acid particles from the aqueous phase, because the particles have an emulsifying action of their own.
N2 yield on Ba0.8La0.2Mn0.8Mg0.2O3 decreased from 70% to 30% on the addition of 1% CO2, which is a much larger negative effect than that seen with O2. The CO2 negative effects are not permanent and this may result from the inhibition of NO adsorption. Co-feeding of H2 as a reductant is effective for increasing NO conversion. This suggests that the catalyst surface was covered with strongly adsorbed nitrate or nitride species which formed by adsorption of NO on oxygen formed by the decomposition of NO, and the removal of this surface species might be the most important step for the NO decomposition reaction. Co-feeding of H2 is also effective for increasing the NO decomposition activity in the presence of CO2. The reaction mechanism was studied by IR measurements which also revealed that the surface of the catalyst was covered with strongly bound nitrate species (NO3−). The addition of H2 to the reaction mixture is effective for NO3− removal and so accelerates the NO decomposition under coexistence of CO2.
Low-resistance metal contacts for CVD-nanocarbon (NC)/cobalt (Co) interconnects have been investigated among contact metals such as Ni, Ti, Au, and Cu. Contact resistivity was independent of contact area owing to low-resistance NC/Co interconnect structure. The lowest contact resistivity and superior adhesion were obtained from Ni. Although the factors for the low contact resistivity were not clear enough from the comparison of work-function difference and adhesion strength for the contact metals, Ni is a promising low-resistivity contact metal for CVD-NC interconnects in the future.
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