کد مقاله کد نشریه سال انتشار مقاله انگلیسی ترجمه فارسی نسخه تمام متن
5407676 1393226 2006 9 صفحه PDF سفارش دهید دانلود رایگان
عنوان انگلیسی مقاله ISI
Polarization transfer from remote protons in 13C CP/MAS
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
سفارش ترجمه تخصصی
با تضمین قیمت و کیفیت
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
Polarization transfer from remote protons in 13C CP/MAS
چکیده انگلیسی
An experimental procedure for CP/MAS polarization transfer from remote 1H nuclear spins is introduced, which is applicable to protonated carbons in organic solids. It is based on preparing a state of non-uniform polarization, where directly bonded 13C-1H nuclei are de-polarized prior to recording the CP buildup curve. This curve is then expected to quantify the polarization transfer from remote protons only. The ability of the cross-polarization/polarization-inversion (CPPI) sequence to generate an initial state suitable for remote 1H CP/MAS scheme is analyzed both theoretically and experimentally. Confining to aliphatic groups, it was found that complete de-polarization of bonded proton is possible in the case of CH, whereas for CH2 and CH3 moieties only a partial de-polarization can be achieved. The theoretical predictions have been verified in practice for the particular case of l-alanine. The significance of the results from fundamental, as well as practical point of view, is also discussed. In particular, it is shown that: (i) the coherent description of polarization transfer under CP/MAS, including 1H polarization redistribution, is valid over time-scales longer than commonly assumed in many treatments of cross-polarization, and (ii) the remote protons polarization transfer curve can be used in combination with the conventional CP/MAS curve to get additional structural and dynamical information in organic systems.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Magnetic Resonance - Volume 183, Issue 1, November 2006, Pages 68-76
نویسندگان
, , , ,
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
سفارش ترجمه تخصصی
با تضمین قیمت و کیفیت