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Date: 19-12-2015
1390
Date: 27-4-2019
1174
Date: 6-7-2017
1404
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NMR active nuclei (group 14 elements)
Table below lists NMR active nuclei for the group 14 elements. Although the isotopic abundance of 13C is only 1.1%, use of 13C NMR spectroscopy is very important. The low abundance means that, unless a sample is isotopically enriched, satellite peaks in, for example, a 1H NMR spectrum, will not be observed and application of 13C as an NMR active nucleus lies in its direct observation. The appearance of satellite peaks due to coupling of an observed nucleus such as 1H to 29Si or 119Sn is diagnostic.
Direct observation of 29Si nuclei is a routine means of characterizing Si-containing compounds. Tin-119 NMR spectroscopy (119Sn being generally favoured over 117Sn for direct observation) is also valuable; the chemical shift range is large and, as with many heteronuclei, δ values may provide an indication of coordination environments.
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دراسة: عدم ترتيب الغرفة قد يدل على مشاكل نفسية
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علماء: تغير المناخ تسبب في ارتفاع الحرارة خلال موسم الحج
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جهود مكثفة وطباعة عشرات الآلاف من المنشورات .. استعدادات العتبة العلوية المقدسة لعيد الغدير الأغر
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