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首页> 外文期刊>Spectrochimica acta, Part A. Molecular and biomolecular spectroscopy >EPR investigations on radiation induced chemical transformations in Pd(ClO4)(2)/i-PrOH/HClO4 system from 77 to 300 K
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EPR investigations on radiation induced chemical transformations in Pd(ClO4)(2)/i-PrOH/HClO4 system from 77 to 300 K

机译:EPR研究Pd(ClO4)(2)/ i-PrOH / HClO4系统中辐射诱导的化学转变从77到300 K

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The EPR studies have been carried out on gamma irradiated samples of Pd(ClO4)(2) in 9M/4M HClO4 in the presence and absence of isopropanol [i-PrOH (5%, v/v)], in the temperature range of 77-300 K. The EPR studies revealed the formation of Pd+ complex, Pd 31 complex and several radicals such as H-center dot, OHcenter dot, ClO3center dot, ClO4center dot and O-3(-) on radiolysis of these systems. Reduction of Pd2+ to Pd clusters could not be observed in the absence of i-PrOH and warming of the irradiated sample finally resulted in recovery of Pd2+ complex. However, in the presence of 5% i-PrOH, strongly oxidizing radicals like OHcenter dot, ClO3center dot and ClO4center dot are suppressed and (CH3)(2)(COH)-O-center dot radical was produced along with reducing species like H-center dot. EPR spectra in these strongly reducing conditions showed formation of Pd+ complex, which on heating above 230 K, disproportionated into Pd-0 and Pd-2, complex and finally lead to formation of Pd metal aggregates. Simultaneously, pulse radiolysis technique has been employed as an alternative method to verify the EPR observations. (c) 2005 Elsevier B.V. All rights reserved.
机译:EPR研究是在存在和不存在异丙醇[i-PrOH(5%,v / v)]的温度范围内,对9M / 4M HClO4中的Pd(ClO4)(2)进行伽马射线辐照的样品进行的。 77-300 K. EPR研究表明,在这些系统的辐射分解过程中,形成了Pd +络合物,Pd 31络合物和几个自由基,例如H中心点,OH中心点,ClO3中心点,ClO4中心点和O-3(-)。在没有i-PrOH的情况下,无法观察到Pd2 +向Pd簇的还原,并且受辐照样品的升温最终导致Pd2 +复合物的回收。但是,在5%i-PrOH的存在下,OH中心点,ClO3中心点和ClO4中心点等强氧化自由基受到抑制,并生成(CH3)(2)(COH)-O中心点自由基以及H等还原物种-中心点。在这些强烈还原条件下的EPR光谱显示形成Pd +络合物,在加热到230 K以上时,它歧化成Pd-0和Pd-2络合物,最后导致形成Pd金属聚集体。同时,脉冲放射分解技术已被用作验证EPR观测值的替代方法。 (c)2005 Elsevier B.V.保留所有权利。

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