Theoretical studies of energy photoemission spectra (XPS) of S and SO2 adsorbed on Ni clusters by Hartree-Fock method
E. Martínez1, A. Rodríguez1, L. Rincón2
1 Lab. de Física de Superficies. Dpto. de Física, Facultad de Ciencias. Universidad de Los Andes, Mérida, Venezuela. e-mail: alfonso@ciens.ula.ve
2 Grupo de Química Teórica. Dpto. de Química, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela.
]]> Recibido el 27 de febrero de 2002.
Abstract
Theoretical results of photoemission energy spectral of the atomic sulfur and of the SO2 molecule, adsorbed over surfaces of Ni(110) and Ni(111) clusters, are reported in this work. Clusters with 11, 13, 15 and 17 atoms of Ni were used for the model. The calculations were done by Hartree-Fock method, and basis sets of type STÓ-NG and p-q1G (p=3,6; q=2,3; N=3,6) were used. The ionization potentials (IP) were interpreted within the Koopmans Theorem. The results obtained for the IP of 1s, 2s and 2p orbitals are 2472.03 eV, 238.14 eV and 173.55 eV, respectively; while for the same orbitals of the sulfur in SO2 these values are 2481.30 eV, 246.61 eV and 182.17 eV. The theoretical results were compared with experimental results reported in the references, and the error ranges are between 5 eV and 30 eV, in agreement with the stardard for the Hartree-Fock method.
Keywords: Adsorption; XPS; Hartree-Fock; sulfur; sulfur dioxide.
Resumen
En este trabajo se reportan resultados teóricos de espectros de energía de fotoemisión (XPS), del azufre en estado atómico y en la molécula de SO2 adsorbidos sobre conglomerados de Ni(110) y Ni(111). Conglomerados con 11, 13, 15 y 17 átomos de Ni fueron usados en cada modelo. El potencial de ionización (PI), fue interpretado usando el teorema de Koopmans. Los resultados obtenidos para el PI de los orbitales 1s, 2s y 2p del azufre atómico son de 2472.03 eV, 238.14 eV y 173.55 eV, respectivamente; mientras que el valor para los mismos orbitales del azufre en la molécula SO2 fueron 2481.30 eV, 246.61 eV y 182.17 eV. Los resultados fueron comparados con datos experimentales reportados en la literatura y el error entre 5 eV y 30 eV es estándar en este método.
Descriptores: Adsorción; XPS; Hartree-Fock; azufre; oxígeno.
]]>PACS: 68.43.Bc; 79.60.-i
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Acknowledgements
The authors thant CONICIT (NM-07 Project), CDCHT (Project: C-1130-02-05-AA) and CeCalCULA of Universidad de Los Andes for the financial support give for this work.
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