Comparative NMR Properties of H2 and HD in Toluene-d8 and in H2/HD@C60

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• 作者：Judy Y.-C. Chen ; Angel A. Mart ; Nicholas J. Turro ; Koichi Komatsu ; Yasujiro Murata ; Ronald G. Lawler
• 刊名：Journal of Physical Chemistry B
• 出版年：2010
• 出版时间：November 18, 2010
• 年：2010
• 卷：114
• 期：45
• 页码：14689-14695
• 全文大小：234K
• 年卷期：v.114,no.45(November 18, 2010)
• ISSN：1520-5207

文摘

Spin−lattice relaxation times, T₁, have been measured from 200−340 K for the protons in H₂ and HD molecules dissolved in toluene-d₈ and incarcerated in C₆₀. It is found that HD relaxes more slowly than H₂ in both environments and at all temperatures, as expected from the smaller values of the spin-rotation and dipole−dipole coupling in HD compared to H₂. More detailed analysis using models developed to describe relaxation in both condensed media and the gas phase indicates that transitions among the rotational states of H₂ occur at a rate similar to those of HD in both toluene-d₈ solution and in C₆₀, in contrast to the situation in gas phase collisions between hydrogen and He or Ar, where the lifetimes of rotational states of HD are markedly shorter than those for H₂. Measurements of the relative ¹H chemical shifts of H₂ and HD, the coupling constant J_HD, and the widths of the HD peaks at various temperatures revealed only small effects with insufficient accuracy to warrant more detailed interpretation.