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الموضوع: Signal Strength

  1. #1
    عضو ذهبي الصورة الرمزية اسراء
    تاريخ التسجيل
    Aug 2011
    المشاركات
    1,442

    افتراضي Signal Strength

    The magnitude or intensity of nmr resonance signals is displayed along the vertical axis of a spectrum, and is proportional to the molar concentration of the sample. Thus, a small or dilute sample will give a weak signal, and doubling or tripling the sample concentration increases the signal strength proportionally. If we take the nmr spectrum of equal molar amounts of benzene and cyclohexane in carbon tetrachloride solution, the resonance signal from cyclohexane will be twice as intense as that from benzene because cyclohexane has twice as many hydrogens per molecule. This is an important relationship when samples incorporating two or more different sets of hydrogen atoms are examined, since it allows the ratio of hydrogen atoms in each distinct set to be determined. To this end it is necessary to measure the relative strength as well as the chemical shift of the resonance signals that comprise an nmr spectrum. Two common methods of displaying the integrated intensities associated with a spectrum are illustrated by the following examples. In the three spectra in the top row, a horizontal integrator trace (light green) rises as it crosses each signal by a distance proportional to the signal strength. Alternatively, an arbitrary number, selected by the instrument's computer to reflect the signal strength, is printed below each resonance peak, as shown in the three spectra in the lower row. From the relative intensities shown here, together with the previously noted chemical shift correlations, the reader should be able to assign the signals in these spectra to the set of hydrogens that generates each. If you click on one of the spectrum signals (colored red) or on hydrogen atom(s) in the structural formulas the spectrum will be enlarged and the relationship will be colored blue.
    Hint: When evaluating relative signal strengths, it is useful to set the smallest integration to unity and convert the other values proportionally.


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  2. #2
    مراقب عام الصورة الرمزية Eiman
    تاريخ التسجيل
    Jul 2011
    الدولة
    الاردن - ماركا
    المشاركات
    14,750

    افتراضي رد: Signal Strength

    مشكوووووورة اسراء
    من جد وجد ....... ومن سار على الدرب وصل

  3. #3
    عضو ذهبي الصورة الرمزية تامر يوسف
    تاريخ التسجيل
    Mar 2012
    المشاركات
    307

    افتراضي رد: Signal Strength

    Thank you Esraa

    عضو في نادي ماركا الأكاديمي


  4. #4
    عضو مميز الصورة الرمزية قمر بلحاج
    تاريخ التسجيل
    Jul 2012
    المشاركات
    5,302

    افتراضي رد: Signal Strength

    جزاكم الله خيرا

    عضو في نادي ماركا الأكاديمي


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