Comparing radical diffusion crossover phenomena in alkanes and alcohols
Comparing radical diffusion crossover phenomena in alkanes and alcohols
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DOI：
10.1016/j.molliq.2023.122220
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发表时间：
2023-06-07
影响因子：
6
通讯作者：
Peric，Miroslav
中科院分区：
文献类型：
--
作者：
Slade，Jakov;Merunka，Dalibor;Peric，Miroslav
我们用电子自旋共振(ESR)研究了氮氧化物自由基在不同温度下在正构烷烃(辛烷到十三烷)和醇(甲醇到正辛醇)中的示踪扩散系数。我们研究和比较了自由基在这些液体中的扩散能力，因为它们的分子相似，但醇由于羟基的氢键表现出不同的结构，这在烷烃中是不存在的。通过关联自由基扩散系数和溶剂自扩散系数，发现了自由基扩散系数在所有液体中的交叉温度行为。这一发现证明了随着温度的降低，从单分子扩散过程到集体过程的转变。然而，醇和烷烃的交叉行为有很大的不同，说明醇的非均相结构影响自由基扩散交叉。
We applied electron spin resonance (ESR) to study tracer diffusivities of a nitroxide radical at various temperatures in the normal alkanes (octane to tridecane) and alcohols (methanol to 1-octanol). We studied and compared radical diffusivities in these liquids because their molecules are similar, but alcohols exhibit heterogeneous structures due to the hydrogen bonding of hydroxyl groups, which is absent in alkanes. The crossover temperature behavior of radical diffusivities was found in all liquids by relating radical diffusivities and solvent self-diffusivities. This finding evidences the transformation from a single-molecule diffusion process into a collective process upon temperature lowering. However, the crossover behavior strongly differs in alcohols and alkanes, indicating that the heterogeneous structure of alcohols affects the radical diffusion crossover.