吸附在活性炭、三氧化二铝和硅胶上分子的核弛豫研究

NUCLEAR RELAXATION STUDIES OF MOLECULES PHYSISORBED ON CHARCOAL，ALUMINA AND SILICA GEL

本文提出核与电子偶极相互作用和自旋扩散两种作用在被吸附到固体多电子表面上的分子弛豫起着重要作用，给出了自旋晶格弛豫时间（Ｔ＿（１ｅ））和相关时间（τ＿ｃ））的关系：Ｔ，式中ｋ对给定固体是常数。吸附在硅胶上甲苯的弛豫数据可用此式描述。得到了甲苯中甲基在不同温度下的τ＿ｃ。，它们在３７４Ｋ到２４０Ｋ间的相关时间在３．５６×１０￣（－９）ｓ到５．７６×１０￣（－８）ｓ范围。由此计算出其活化能为１５．０ｋＪ／ｍｏｌ。

Electron-nuclear dipolar interaction and spin-diffusion play very important roles in the re-laxation processes of molecules adso rbed o n solids containing surface eleetrons， such aS charcoal，alumina and silica gel．According to this relaxation rnechanism，the relation between spin-lattice relaxation time（T_(1e)）and correlation tim-（τ_c）was obtainted：k is a con-stant for a given solid． It was found that the relaxations of toluene adsorbed on silica gel were interpretted well by this formula， The correlation times at dirrerent temperatures and the activqtion energy（E_a=15．0kJ／mol） of methyl group in toluene adsorbed on silica gel were obtained．The correlation times are in the range of 3．56 × 10^(-9)-5．76× 10^(-8)s during 374 K and 240 K.