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Chemical Bonding between Cu and OxygenCopper Oxides vs O 2 Complexes: A Study of CuO x ( x = 0−6) Species by Anion Photoelectron Spectroscopy

1997; American Chemical Society; Volume: 101; Issue: 11 Linguagem: Inglês

10.1021/jp9631442

1520-5215

Hongbin Wu, Sunil R. Desai, Lai‐Sheng Wang,

Advanced Chemical Physics Studies

An extensive photoelectron spectroscopic study on the CuOx- (x = 0−6) species is presented. The photoelectron spectra of these species are obtained at four detachment photon energies: 2.33, 3.49, 4.66, and 6.42 eV. The spectra of the copper atom are included to show the dependence of the detachment cross sections on the photon energies. An intense two-electron transition to the 2P excited state of Cu is also observed in the 6.42 eV spectrum of Cu-. For CuO-, we observe an excited state of the anion, as well as photodetachment transitions to charge transfer excited states of CuO (Cu2+O2-). Six transitions are observed for CuO2- at 6.42 eV, revealing all six valence molecular orbitals of the linear OCuO molecule. CuO3- is observed to undergo photodissociation at 3.49 eV to give an internally hot CuO- plus O2. It is shown to have an OCuO2 type of structure, and its electronic structure can be viewed to be due to that of CuO perturbed by an O2. For CuO4-, two isomers are observed. One of them undergoes photodissociation at 3.49 eV, and it is shown to be a Cu/O2 complex, Cu(O2)2-. The second isomer yields spectra identical to that of the linear OCuO- with a slight energy shift and is concluded to be an OCuO- solvated by a very weakly bonded O2, (OCuO-)O2. CuO6- is shown to exhibit similar behaviors as CuO4- with a Cu/O2 complex, Cu(O2)3-, and an O2-solvated CuO2-, (OCuO-)(O2)2. The CuO5- spectra are observed to be similar to that of CuO3-, and it is shown to be due to a CuO3- solvated by an O2, (OCuO2-)O2.