1. INTRODUCTION OF SPECTROSCOPY
“It is the interaction of electro-magnetic waves with
matter and study of that electro-magnetic radiation is
known as spectroscopy.”
“When a charge particle is accelerated magnetic and
electric field are produced which vibrates vertically
towards the direction of transmission.”
Spectrum :-- when a radiation is passed through
prism or grating then its splitting in the different wave-
length is called spectrum
(1 )Continuous spectrum : When any light source
passes through prism then it get dispersed in to
continuous bands of different colours known as
(2) Emission spectrum : Spectrum produce by
emitted radiation is known as emission
(3) Absorption spectrum : Spectrum produce by
absorption of electromagnetic radiation of
2. NMR-Nuclear Magnetic Resonance Spectroscopy :-
NMR involves the interaction between an oscillating magnetic field of
E.M. radiation and the magnetic energy of the nuclei when these are
placed in an external static magnetic field. The sample absorbs E.M.
radiation in RADIO WAVE region.
NMR technique consist in exposing the protons in an organic molecule
to a power- full field. The protons will posses at different frequencies,
now we irradiate these processing protons with steadily changing
frequencies and observe the frequency at which absorption occur.
Also NMR is a spectroscopy technique which is based on absorption of
electromagnetic radiation in the radio frequency region (4 to 900Mhz ) by
the nuclei of the atom.
At some value of the field strength, the energy required to flip the
protons matches the energy of the radiation, Absorption occurs and a
signal is observed. Such a spectrum is called NMR SPECTRA.
CHEMICAL SHIFT:- The ratio of difference in the
position of a particular proton from the absorption
position of a reference proton is known as the
chemical shift of the particular proton, or the
shifts(compared with a reference)in the position of
NMR absorptions which arise due to the shielding
& deshielding of protons by electrons are called
Why TMS is used as reference compound ?
1. It is chemically inert
2. Magnetically isotropic
6. Soluble in most of organic solvents.
7. It gives a single sharp absorption peak at
higher field than almost all organic
The interactions between the spins of neighbouring nuclei
in a molecule may cause the splitting of NMR signal in the
spectrum, this is known as Spin-Spin coupling.
NMR signal of (a) proton show triplet due to protons (b).
NMR signal of (b) protons show quartet due to protons
APPTICATION OF NMR-SPECTROSCOPY:-
1. Identification of structural isomers.
2. Detection of hydrogen bonding.
3. Detection of aromaticity.
4. Detection of electronegative atom or group.
5. Conformational analysis.
6. Detection of double bond character.
7. Keto-enol tautomerism.
8. Elemental and Quantitative analysis.
INTRODUCTION TO SPECTROSCOPY……Donald L pavia
Lampan george s, kriz james r. Vyvyan
ELEMENTARY ORGANIC spectroscopy by……Y.R