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13 C relaxation and anisotropic molecular reorientation in liquid dibromomethane
Author(s) -
Nance Lewis E.,
Nealey Marty R.,
Rodriguez A. A.
Publication year - 1990
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260280104
Subject(s) - chemistry , rotational diffusion , degenerate energy levels , relaxation (psychology) , anisotropy , spin–lattice relaxation , scalar (mathematics) , molecule , moment of inertia , lattice (music) , molecular physics , computational chemistry , nuclear magnetic resonance , classical mechanics , physics , quantum mechanics , psychology , social psychology , geometry , mathematics , organic chemistry , nuclear quadrupole resonance , acoustics
Although dibromomethane is a simple molecule, little work has been directed toward the analysis of its reorien‐tational motion. This is surprising, since two components of its inertia tensor are nearly degenerate and may, in principle, be treated as a quasi‐symmetric top. The 13 C spin–lattice relaxation times and nuclear Overhauser enhancements were measured at various temperatures in the liquid phase. Field‐dependent measurements indicated the presence of the scalar relaxation mechanism. Calculated rotational diffusion constants were found to be in reasonable agreement with values predicted by the J ‐diffusion model of inertially controlled reorientation. The results show that scalar coupling of the second kind is an important mechanism for 13 C spin–lattice relaxation in this molecule. The data further indicates that dibromomethane may indeed be exhibiting quasi‐symmetric top behavior of this phase.