کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5407047 1393200 2008 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The utility of phase alternated pulses for the measurement of dipolar couplings in 2D-SLF experiments
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
The utility of phase alternated pulses for the measurement of dipolar couplings in 2D-SLF experiments
چکیده انگلیسی
The measurement of hetero-nuclear dipolar coupling using two-dimensional separated local field (SLF-2D) NMR experiments is a powerful technique for the determination of the structure and dynamics of molecules in the solid state and in liquid crystals. However, the experiment is sensitive to a number of factors such as the Hartmann-Hahn match condition, proton frequency off-set and rf heating. It is shown here that by the use of phase alternated pulses during spin-exchange the effect of rf mismatch on the dipolar coupling measurement can be compensated over a wide range of off-sets. Phase alternation together with time and amplitude modulation has also been considered and incorporated into a pulse scheme that combines spin exchange with homonuclear spin decoupling based on magic sandwich sequence and named as SAMPI4. Such time and amplitude averaged nutation experiments use relatively low rf power and generate less sample heating. One of these schemes has been applied on liquid crystal samples and is observed to perform well and yield spectra with high resolution.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Magnetic Resonance - Volume 194, Issue 2, October 2008, Pages 237-244
نویسندگان
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