THIS IS THE BASICS OF UV VISIBLE SPECTROSCOPY. By reading this slide one can easily understand about uv-visible spectroscopy. this topic is for physics student,chemistry student,engineering graduate as well as pharmacy student

1. UV-VISIBLE SPECTROSCOPY
PURNENDU PAL
BANKURA UNIVERSITY
BANKURA, WEST BENGAL

2. Electromagnetic spectrum:
• Electromagnetic radiation consists of all kind of radiation ranging
from 1 Hz to1025 Hz.

3. SPECTROSCOPY
• It is the branch of science that deals with the study of interaction of
electromagnetic radiation with matter
• Absorption spectroscopy: uv-vis spectroscopy, IR spectroscopy
• Emission spectroscopy: mass spectroscopy

4. UV-VISIBLE SPECTROSCOPY:
• The principle of uv-visible spectroscopy is based on the absorption of
uv/visible light by chemical compounds,which results in the
production of distinct spectra.
• When a matter absorbs uv radiation the electron present in it
undergo excitation .This cause them to jump from a ground state to
an excited state.

5. Beer-Lambert law:
• The uv vis spectroscopy follows the beer lambert law which state
that-
• The absorbance is directly proportional to the path length of the
sample(b).
• The absorbance is directly proportional to the concentration of the
sample(c).
• Absorbance A=ξbc, where ξ is constant.

6. Instrumentation:
Components of uv-vis spectrometer –
• Source
• Monochromator
• Sample container/sample cell
• Detector

7. Radiation source:
UV radiation source:
• Deuterium lamp
• Hydrogen lamp
• Tungsten lamp
• Xenon discharge lamp
• Mercury arc lamp
Visible radiation source:
• Tungsten lamp
• Mercury vapour lamp

8. Monochromator:
All the light sources produce a broad-spectrum white light. To narrow
the light down to a selected wavelength band, the light is passed
through a monochromator. A monochromator consists of:
• An entrance slit: polychromatic radiation enters themonochromator through the
entrance slit
• Dispersion device: it spread the light into different wavelengths (like a rainbow) and
allow the selection of a nominated band of wavelengths.
• The exit slit: By moving the dispersing element or the exit slit,radiation of only particular
wavelength leaves the monochromator through the exit slit.

9. SAMPLE CONTAINER:
• It is transparent cells that hold the materials under study and we used
to introduce sample into the light path. Glass and plastic absorb
strongly below 310 nm and arenot useful for measuring absorbance
below that below that wavelength. Quartz and silica cells are used
when measuring absorption of uv wavelengths by a solution. Since
they are transparent to wavelength than 180 nm.

10. Single beam uv-vis spectrometer
Double beam uv-vis spectrometer

11. Detector:
• A detector converts the light from the sample into on electrical signal.
• Spectrometer normally contain either a photomultiplier tube detector
or a silicon diode detector.

12. Application of uv-vis spectrometer:
• Detection of Impurities
• Structure of organic compounds.
• Kinetics of reaction can also be studied using UV spectroscopy. The UV
radiation is passed through the reaction cell and the absorbance changes
can be observe
• Molecular weights of compounds can be measured spectrophotometrically
by preparing the suitable derivatives of these compounds.