Mingrong Ji

The interaction of oxygen with niobium studied by XPS and UPS

Abstract The adsorption and desorption of O2 on Nb (110) surface are studied by XPS and UPS. The changes of structure in the electron energy distribution curves for different oxygen exposures and desorption temperatures are correlated with formation of different oxides. The result indicates a reversible conversion of Nb, NbO and Nb2O5 in the absorption and desorption process.

CORRELATION BETWEEN ELECTRONIC STATES OF OXYGEN AND COPPER IN Y-BA-CU-O DOPED SYSTEMS

Abstract The electronic states of copper and oxygen in YBaCuO and five doped systems (Ba is doped by Sr, Ca;Cu by Zn, Al, Sn, respectively) are studied by XPS, the oxygen contents of samples are determined by thermogravimetric analysis. The experimental results show that there is strong correlation between the electronic states of copper and oxygen. The samples, in which the difference of two states of O 1s is indistinct and the oxygen content high, show partial Cu 3+ oxidation state. In contrast, the samples, in which the difference of two states of O 1s is clear and the oxygen content low, show entire Cu 2+ oxidation state. Comparing these results with the superconductivity of samples, it is found that Cu 3+ state has no direct relationship with superconductivity. The experimental results demonstrate that Cu 3+ state is only the result of the charge balance in the systems.

PES study of amorphous alloy Fe40Ni40P20

Abstract The electron structure of amorphous Fe 40 NI 40 P 20 has been investigated before and after annealing by XPS and UPS (HeI, HeII). It is shown that the spectra of UPS were modified obviously by various degree of annealing. Composition and chemical states of the components on the surface of the sample are also presented and the effect of structural ordering on the density of states (DOS) of the valence band is discussed.