UV Visible spectroscopy
Spectroscopy:-The branch of science concerned with the investigation and
measurement of spectra produced when matter (Atoms or Molecules)
interacts with electromagnetic radiation (EMR).
Instruments
When a molecule absorbs UV radiation of frequency ν sec–1
, the electron in that molecule
undergoes transition from a lower to a higher energy level or molecular orbital
Ultraviolet and visible spectroscopy deals with the recording of the absorption of
radiations in the UV and visible regions of the electromagnetic spectrum.
responsible for imparting colour to
the compound. Nitro -compounds are generally yellow in colour. Clearly, nitro group is
the chromophore that imparts yellow colour
Auxochrome
any group which does not itself acts as a
chromophore but whose presence shift s of the absorption band towards the red end
of the s pectrum
-OH, -NH3
Spectral shift
Hyperchromic
Hypochromic
Hypsochromic
Bathochromic
intensity of absorption maximum
increases,
the intensity of absorption maxim um
decreases,
absorption maximum is shifted
towards shorter wavelength
absorption maximum is shifted
towards longer wavele ngth
BEER & LAMBERT’S LAW
Radiation Source
Wavelength Selector:
Cells or Cuvettes
Detector:
Both the tungsten and D 2 lamp
Monochromator
holding the sample solution and the pure solvent
photo -emissive cells or phototubes
and photomultiplier tubes.
Slit
Filter
Application
Detection of Functional Groups:
Distinction in Conjugated and Non-Conjugated Compounds
Determination of Strength of Hydrogen Bonding
FARJINA FIROZ AKHTAR
19PH01