Watching silver clusters grow in zeolites: direct probe Fourier transform-far-infrared spectroscopy of the red form of fully silver ion exchanged zeolite A
Watching silver clusters grow in zeolites: direct probe Fourier transform-far-infrared spectroscopy of the red form of fully silver ion exchanged zeolite A
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观察沸石中银簇的生长：完全银离子交换沸石 A 的红色形式的直接探针傅立叶变换远红外光谱
DOI：
10.1021/j100257a031
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
G. Ozin
中科院分区：
文献类型：
--
作者：
M. Baker;J. Godber;G. Ozin
本文首次用FT-Far-IR光谱研究了真空热脱水的红色形式的Ag/sub12/-A。在175-50 cm/sup-1/波数范围内观察到银-银骨架模式，并与立方八面体笼子中的(Ag/sub3//sup x+/)/subn/赝团簇的红外活性骨架振动有关。在低温范围内将(Ag/sub3//subx+/)/sub2/在低温范围内还原到130/sup 0/C的受控H/sub2/还原似乎经过至少两个可检测的步骤，以产生立方八面体包裹的还原形式的(Ag/sub3//subx+/)/subn/。这个还原的团簇与O/sub2/at 200-400/sup 0/C的相互作用将还原过程逆转为原始的(Ag/sub3//subx+/)/subn/立方八面体定位的伪团簇。相反，在200/sup 0/C处，(Ag/sub3//subx+/)/subn/red形式的H/sub2/还原更严重，将团簇转变为外部的银微晶。这些样品延长的450/sup 0/CO/sub2/氧化部分恢复了原始的(Ag/sub3//subx+/)/subn/赝团簇。每个原子的银-银键伸缩力常数随着配位数的增加而减小，最高可达12个近邻原子的体银值。参考文献13篇，附图5篇。
The red form of vacuum thermally dehydrated Ag/sub 12/-A has been studied for the first time by FT-far-IR spectroscopy. Silver-silver skeletal modes are observed in the wavenumber range 175-50 cm/sup -1/ and are associated with the IR-active skeletal vibrations of a (Ag/sub 3//sup x+/)/sub n/ pseudocluster located in cuboctahedral cages. Controlled H/sub 2/ reduction of (Ag/sub 3//sub x+/)/sub 2/ in the low-temperature range room temperature to 130/sup 0/C appears to proceed through at least two detectable steps to yield a cuboctahedrally entrapped, reduced form of (Ag/sub 3//sub x+/)/sub n/. The interaction of this reduced cluster with O/sub 2/ at 200-400/sup 0/C reverses the reduction process to the original (Ag/sub 3//sub x+/)/sub n/ cuboctahedrally located pseudocluster. By contrast, more severe H/sub 2/ reduction of the (Ag/sub 3//sub x+/)/sub n/ red form at 200/sup 0/C transforms the cluster to external silver microcrystals. A prolonged 450/sup 0/C O/sub 2/ oxidation of these samples partially reinstates the original (Ag/sub 3//sub x+/)/sub n/ pseudocluster. The silver-sliver bond stretching force constant per atom decreases with coordination number up to the bulk silver value of 12 nearest neighbors. 13 references, 5 figures.