Surface models for the adsorption of a calcium beta-diketonate complex on calcium sulfide

被引:3
作者
Calhorda, MJ
Veiros, LF
Niinisto, L
机构
[1] IST,P-1096 LISBON,PORTUGAL
[2] CQE,P-1096 LISBON,PORTUGAL
[3] HELSINKI UNIV TECHNOL,INORGAN & ANALYT CHEM LAB,FIN-02150 ESPOO,FINLAND
来源
ACTA CHEMICA SCANDINAVICA | 1996年 / 50卷 / 10期
关键词
ATOMIC LAYER EPITAXY; THIN-FILMS;
D O I
10.3891/acta.chem.scand.50-0862
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Extended Huckel tight-binding calculations were used to study the bonding modes of beta-diketonate precursor complexes to three possible adsorption sites of the S(111) surface of calcium sulfide, in order to study gas phase deposition of thin layered calcium sulfide. Molecular models were also used for comparison. The three-fold site seems to be favored for adsorption, as stronger calcium-surface bonds are formed. The bonding occurs through donation from surface sulfur lone pairs into empty orbitals of the calcium complex. These acceptor orbitals are mainly located on the calcium atoms and have a strong calcium-oxygen antibonding character. Though the large energy difference between calcium and sulfur orbitals is responsible for weak interactions, many calcium-oxygen antibonding levels become also calcium-sulfur bonding, and their energy falls below the Fermi level. The Ca-O bonds weaken, thus activating the adsorbed beta-diketonate complex toward loss of the ligand.
引用
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页码:862 / 870
页数:9
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