کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5406896 1393193 2009 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Double resonance experiments in low magnetic field: Dynamic polarization of protons by 14N and measurement of low NQR frequencies
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
Double resonance experiments in low magnetic field: Dynamic polarization of protons by 14N and measurement of low NQR frequencies
چکیده انگلیسی
The possibilities of dynamically polarizing proton spin system via the quadrupole 14N spin system in low magnetic field are analyzed. The increase of the proton magnetization is calculated. The polarization rate of the proton spin system is related to the transition probabilities per unit time between the 14N quadrupole energy levels and proton energy levels. The experiments performed in 1,3,5-triazine confirm the results of the theoretical analysis. A new double resonance technique is proposed for the measurement of nuclear quadrupole resonance frequencies νQ of the order of 100 kHz and lower. The technique is based on magnetic field cycling between a high and a low static magnetic field and observation of the proton NMR signal in the high magnetic field. In the low magnetic field the quadrupole nuclei and protons resonantly interact at the proton Larmor frequency νH = νQ/2. The quadrupole nuclei are simultaneously excited by a resonant rf magnetic field oriented along the direction of the low static magnetic field. The experimental procedure is described and the sensitivity of the new technique is estimated. Some examples of the measurement of low 14N and 2H nuclear quadrupole resonance frequencies are presented.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Magnetic Resonance - Volume 199, Issue 2, August 2009, Pages 199-207
نویسندگان
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