Infrared and photoelectron spectroscopic studies of ethyl and octyl xanthate ions adsorbed on metallic and sulfidized gold surfaces
Infrared and photoelectron spectroscopic studies of ethyl and octyl xanthate ions adsorbed on metallic and sulfidized gold surfaces
复制标题
金属和硫化金表面吸附的乙基和辛基黄原酸离子的红外和光电子能谱研究
DOI：
10.1021/la00027a021
复制
发表时间：
1993
期刊：
影响因子：
3.9
通讯作者：
B. Liedberg
中科院分区：
文献类型：
--
作者：
A. Ihs;K. Uvdal;B. Liedberg
利用红外反射吸收光谱（IRAS）和x射线光电子能谱（XPS）研究了乙基和辛基黄药离子在金属金表面和硫化氢硫化金表面的吸附。利用金（I)乙基黄原酸盐的KBr透射光谱计算出的光学常数n (v)和k {v），并与乙基黄原酸盐离子吸附在金上的实验反射吸收（RA）光谱进行了比较。在实验和计算的RA光谱之间的相对强度有相当大的差异。在完全单层覆盖下，形成高度有序的结构，其中烷基黄原酸盐离子通过两个硫原子与表面配位。辛基黄药在3000 cm-1附近的亚甲基拉伸振动频率进一步表明烷基链具有完全延伸的全反式之字形构象。在亚单层覆盖下，黄原酸离子的取向和/或构象似乎发生了变化，辛基黄原酸离子的烷基链也发生了构象紊乱。在硫化金表面上只能得到少于单层的覆盖物。这可能是由于吸附的H2S阻塞了吸附位点。黄原酸盐离子与表面的配位不同于在纯金上的亚单层覆盖，并且烷基链构象紊乱。
Infrared reflection absorptionspectroscopy (IRAS) and X-ray photoelectronspectroscopy (XPS) have been used to study the adsorption of ethyl and octyl xanthate ions on metallic gold surfaces and gold surfaces sulfidized by exposure to H2S. The experimental reflection-absorption (RA) spectra of ethyl xanthate ions adsorbed on gold are compared with the calculated RA spectrum, which is based on the optical constants n (v) and k {v) derived from the KBr transmission spectrum of gold (I) ethyl xanthate. A considerable difference in relative intensitiesbetween the experimental and calculated RA spectra is observed. At full monolayer coverage highly ordered structures are formed where the alkyl xanthate ions are coordinated to the surface through both sulfur atoms. The frequencies of the methylene stretching vibrations near 3000 cm-1 for octyl xanthate furthermore suggest that the alkyl chain has a fully extended, all trans, zigzag conformation. At submonolayer coverage the orientation and/or conformation of the xanthate ions appears to be changed and the alkyl chains of the octyl xanthate ions are also conformationally disordered. On sulfidized gold surfaces only coverages less than a monolayer could be obtained. This is probably due to blocking of the adsorption sites by adsorbed H2S. The coordination of the xanthate ions to the surfaceis different than for submonolayer coverages on pure gold, and the alkyl chains are conformationally disordered.