The hole-concentration (x) dependence of the three-dimensional energy-momentum dispersion in (Bi, Pb)2(Sr, La)2CuO(6+delta) has been investigated by angle-resolved photoemission spectroscopy. For a heavily overdoped sample of T(c) < or = 0.5 K, an energy dispersion of approximately 10 meV in width is observed in the vicinity of the (pi, 0) point with varying momentum along the c axis (k(z)). This k(z) dispersion is zero for underdoped, optimally doped, and slightly overdoped samples up to a doping level corresponding to T(c) = 22 k. At higher doping levels we observe significant dispersion of the order of 10 meV (sample with T(c) < or = 0.5 K). This is clear evidence that at a doping value corresponding to T(c) = 22 K, a crossover from two- to three-dimensional electronic structure occurs.

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Azaferrocene has two active sites of iron and nitrogen atoms. Drastic change of the oxidation state in iodine oxidation of azaferrocene is observed by introducing the methyl substituents into the pyrrole ring, while all the N-methylates show a similar electronic state. It was revealed that an introduction of methyl substituent to the pyrrole ring promotes the oxidation of nitrogen atom in pyrrole ring more than the central iron atom.