Chemical Science Short Notes: Nuclear Magnetic Resonance! (Download PDF)

By Renuka Miglani|Updated : May 30th, 2023

Hello Aspirants,

Are you looking for some short and reliable notes during your CSIR-NET preparations? Then, you have come to a perfect place!

Candidates preparing for their CSIR NET exam might need to get some short study notes and strategies to apply while preparing for the key exam of their life. At this point, We at Byjus Exam Prep come up with short notes on Nuclear Magnetic Resonance, which comes under the Inorganic Chemistry section of the Chemical Science syllabus. 

Our experienced subject matter experts have meticulously designed this set of short notes on Nuclear Magnetic Resonance to give you the most standard set of study materials to be focused upon. In this cut-throat competitive world, students need to prepare themselves with the best study materials to help them learn and for their future. So, here we are offering the best study notes that are reliable and can be used by the students during their preparations for the upcoming CSIR-NET 2023 exam.


Nuclear Magnetic Resonance (Download PDF)


Nuclear Magnetic Resonance (NMR) is part of the discipline of Magnetic Resonance and includes NMR, Electron Paramagnetic Resonance (EPR or ESR) and Nuclear Quadrupole Resonance (NQR). Nuclear Magnetic Resonance (NMR) spectroscopy takes advantage of the magnetic properties of certain nuclei and records the absorption of energy between quantized nuclear energy levels. In an NMR experiment, the spectrometer is tuned to the frequency of a particular nucleus and the spectrum reveals all such nuclei in the molecule being investigated.

Nuclei may have spins of zero or greater than zero in units of ½, because of how the protons and neutrons are arranged relative to one another. There are three possible conditions:

No. of Protons No. of Neutrons


EvenEven0 → No MNR


OddEvenHalf-Integral Spin
  1. For I = 0: Nuclei that have both an even number of protons and an even number of neutrons will have zero net nuclear spin.
  2. I = ½: The spin -1/2 nuclei are the most important class for NMR spectroscopy.
  3. I > ½: These are known as the quadrupole nuclei, because such spins induce a so-called quadrupole magnetic moment.

For a substance to be NMR active, the I (Nuclear spin) should not be equal to 0, because these types of nuclei are unable to act like a small magnet. Those are preferred species for NMR for which spin of I = ½. These nuclei all give NMR signals that obey the same rules as do the familiar 1H spectra. The highly abundant nuclei 1H, 19F and 31P are the most important NMR nuclei to give good spectra. Some of the more common spin ½ nuclei are listed in the shorter table shown below. 


Natural abundance (%)
































Working Principle:

Any spinning charge body generates a magnetic field. Therefore, a nucleus of an atom which possesses both electric charge and mechanical spin behaves as a tiny spinning bar magnet, and this forms the basis of Nuclear Magnetic Resonance.



Dipole moment of a spin nucleus is given by 


µ can be oriented so that its component is integral or half integral in the reference   direction. The external magnetic field tries to align the nucleus in its direction by applying a torque on the nucleus. The spinning nucleus instead of aligning in the field direction makes a processional motion about the field direction. i.e the axis of spin describes a cone about the field direction. Such precession which is shown by the spinning nucleus is known as Larmor Precession.



Concluding theory of NMR:

Nucleus is exposed to electromagnetic radiation of suitable frequency and subjected to an external magnetic field which is adjusted to make the processional frequency of the nucleus equal to the frequency of the radiation. Nucleus absorbs the right amount of energy and makes a transition from energy level to the next and generates a current which is further detected by the detector. The NMR signal of the nucleus is highly specific to the nucleus under study. The widest distributed magnetically active nucleus in organic compounds is H- atom and the corresponding NMR is referred to an PMR of proton Magnetic Resonance.

The points of interest in the study of NMR are: -

  1. No. of signals 
  2. Position of signals and chemical shift.
  3. Intensity of signals.
  4. Splitting of signals or Spin – coupled.

Multinuclear NMR:

If an element has more than one NMR active nuclei, then the most appropriate Nuclei be based on the following Nuclear Properties.


Nuclei under Consideration 

(a). I = ½ High abundance(1H)

(b). I = ½ Low abundance(13C)

(c). I > ½ Low abundance (15N)

Splitting of lines by the presence of another nuclei is given by:


Here, n= no. of equivalent proton

           I= nuclear spin

There is total 7 cases are formed while any nucleus is considered for NMR spectroscopy and these are:


1. Molecule with one type of spin I = ½ & conc. Nuclei


H2, F2, P4, P4S3, BrF3, BrF5, SF4, SF6, H2S, H2


2. Two I = ½, conc. Nuclei.


HF, PH3, PF3, PF5, PCl2F3


3. Three = I = ½, conc. Nuclei




4. One I = ½, conc. Nuclei + I = ½ dilute Nuclei


2 NMR Active Nuclei

CH4, Hydrocarbons, SiH4


5. Two, I = ½ conc. Nuclei + one, I = ½ dilute Nuclei


3 NMR Active Nuclei

CH2F2, CH2=CF2 

6. Two types of I = ½ spin dilute and one type of ½ spin conc. 


The NMR Active Nuclei



7. Molecule with Quadrupole Nuclei. 


CDCl3, NH3,NH4+

Download PDF for Short Notes on Nuclear Magnetic Resonance (NMR)



write a comment

Follow us for latest updates