13C Chemical Shifts in Adsorption Systems: Molecular Motions, Molecular Orientations, Qualitative and Quantitative Analysis

摘要: The Pines-Gibby-Waugh (1) technique, supplemented by magic angle spinning, has been applied to fibrous polyacetylene, benzene (enriched in 13C) adsorbed on oriented clay, as well organic functional groups (at natural 13C abundance) chemically bound silica and alumina. principal values for the shift tensors of both cis trans polyacetylene are given. Benzene molecules hectorite “stand” edge between clay layers executing fast hexad axis rotation a motion (probably diffusion interlayer space) which gives effect molecular about normal platelets. This latter is effectively quenched below 230K. Thus new technique determining orientation state established. Magic spinning allowed “best case” linewidth 42 Hz (13C frequency — 15 MHz) ≡ Si-O- Si(CH3)3. For Si-O-SiO3 only “doublet” was resolved, could be fit expected quartet using 50 Hz. These other specimens contained 3–15% carbon weight. intensity under “standard conditions” single line spectrum trimethylsilyl group proportional content specimen may serve measure degree silylation (hydrophobicity) or even surface area.