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Nickel(II) chelate of 2–picolylamine has been studied spectrophotometrically in aqueous solution at 25°C and at an ionic strength of 0.3 M. The formation of pink color chelate was pH dependent, and the optimum pH range was between 7.0 to 8.5. Its mole ratio of ligand to nickel(II) ion was found to be 3 to 1 stoichiometry and the formation constant, logK, was determined as 13.31 ± 0.10. By using the wavelength 535 run, determination of trace amount of nickel(II) ion with the sensitivity of 5.28 τ/Cm2 was possible. Enthalpy and entropy changes characterizing the formation of the chelate have been calculated as follows: ΔG°=–8.15Kcal mole‐1, ΔH°=–9.65 Kcal mole‐1, ΔS°=28.5eu mole‐1.

The atomic structures and chemical states of active and inactive dopant sites in n-type and p-type 4H-SiC(0001) substrates have been investigated by X-ray absorption near edge structure (XANES) and photoelectron spectroscopy (PES). In N atom-doped n-type 4H-SiC(0001), the PES results indicated that a N− C species was formed near the surface. XANES simulations showed that SiNx and N−C species were attributed to active and inactive dopant states, respectively. Angle-resolved XANES measurements showed that the N−C species acted as an inactive dopant site in N-doped 4H-SiC(0001). In Al-doped p-type 4H-SiC, PES analysis revealed that a single chemical state was present at the Al-doped 4H-SiC. The simulated XANES spectra showed that the Si site in 4H-SiC(0001) was replaced by an Al dopant atom, which was the active dopant site. Furthermore, relaxation of the local structure around the Al dopant in Al-doped 4H-SiC(0001) was observed due to bond stretching.

Cobalt (II) and copper (II) chelates of 2‐picolylamine have been studied spectrophotometrically in aqueous solution. Formation of 2‐picolylamine chelates was pH dependent, and the optimum pH range of the cobalt (II) chelate was at pH 8.8‐9.6, and copper(II) chelate at 4.7‐6.8, respectively. The mole ratio of 2‐picolylamine to both of metal(II) ions was found to be 2 to 1 stoichiometry. The spectrophotometric sensitivities are 0.23γ of Co/Cm2 and 8.9γ of Cu/Cm3, at 373 mμ, pH 9.0 for Co(II) chelate and 588 mμ, pH 6.0 for Cu (II) chelate. The stability constants (logK) of the chelates CoL22+ and CuL22+ have been evaluated at a constant ionic strength of 0.10 at 20, 25, 30, 35 and 40°C. Enthalpy and entropy changes characterizing the formation of the chelates have been calculated at 25°C The results are collected as follows: