Nmr spectroscopy

nmr spectroscopy

1. NMR SPECTROSCOPY Submitted to -: Dr.Monika Asthana Dept.of Biotechnology school of life science, DBRAU Agra. Submitted by-: Prashant sharma biotechnologist

2. INTRODUCTION NMR spectroscopy stands for nuclear magnetic resonance spectroscopy NMR spectroscopy is a analytical technique which is used in characterizing organic molecules by identifying carbon hydrogen frameworks This technique utilizes the magnetic properties of some nmr active substances Nmr spectroscopy works on the spin of the nucleus as well as the standard absobtion phenomenon of spectroscopy

3. HISTORY OF NMR The Purcell group at Harvard University and the Bloch group at Stanford University independently developed NMR spectroscopy in the late 1940s and early 1950s.  Edward Mills Purcell and Felix Bloch shared the 1952 Nobel Prize in Physics for their discoveries Prof. R.R. Ernst received the Nobel Prize in Chemistry, in 1991, for the development of the NMR techniques

4. TYPES OF NMR There are various types of NMR SPECTROSCOPY but the most common are of two types which are charachterized on the basis of atoms used 1 H1 NMR -: it is used to study the types and number of H atoms 2 C13 NMR -: it is used to study the types of different carbon atoms

5. Source of NMR The source of nmr is radio waves which have a ong wavelength having more than 10 7 nm and thus low frequency and energy When these low energy waves interact with a molecule they can change the nuclear spins of the some elements including 1 H and 13 C

6. PRINCIPLES OF NMR The principle behind NMR comes from The spin of the nucleus and it generates a magnetic field without an external applied magnetic field, the nuclear spins are random in directions But when an external field is applied the nuclei align themselves in the direction of the magnetic field or opposite this is called spin flip

7. If an external field is applied , an energy transfer is possible between ground state to excited state When the spin returns to the ground state the absorbed radiofrequency energy is emitted at the same frequency level This emitted radio frequency gives the nmr spectrum of the concerned nucleus

8. NMR spectrum

9. INSTRUMENTATION 1.Sample holder 4.sweep generator 2permanent magnet 5.radio frequency trasmitter 3.Magnetic coils 6.radio frequency receiver 7. read out systems

10. . 1.Sample holder :- it is a glass tube used to hold the sample and the solvent it is 8.5 cm long and 0.5cm in diameter 2.permanent magnet:- it is used to provide the magnetic field this magnetic field id homogeneous in nature and is u around 60-100MHZ 3.Magnetic coils:- these are electromagnets when there is a flow of current these magnetic coils generate or induce magnetic field 4. Sweep generator:- this part of the instrument is used for maintaining a equal amount of magnetic field passing through the sample

11. 5.Radio frequency transmitter-: it is the radio transmitter coil that produces a short powerfull pulse of radio wave 6.Radio frequency receiver- : it is a radio coil that detects the radio frequency emitted by the nuclei as they relax to a lower energy state 7. Readout system-: it is the computer that records and analyses the data and records are then shown in the form of graph

12. Solvents used in NMR The following solvents are used in which hydrogen is replaced by dueterium CCl4- carbon tetra chloride CS2 –carbon disulphide CDCl3- Deutieiochloroform C6D6-Hexa deutriobenzne D2O- deutrim oxide

13. What is chemical shift?

14. Working of NMR The sample is dissolved in a solvent usually CDCl3and placed in a magnetic field A radiofrequency generator then irradiates the sample with a short pulse of radiation ,causing resonance of the proton When the nuclie fall back to their lowest energy state ,the detector mausres the energy released and a spectrum is recorded in the form of graph

15. Applications of NMR