3. SS SSee hh uu
byby

4. 1. Science and History
2. Laws
3. Internal structure of UV-Vis spectrum instrument
4. Monochromatic light
5. λmax
6. Source of UV-Vis light
7. Spectrophotometry, Transmittance & Absorbance
8. Working & Handling of UV-Vis spectrum instrument

5. "Imagination is more important than
knowledge."

6. “Bouguer (1729)
Lambert (1760)
“ Bernard (1852)
“Beer (1852)
“Beer- lambert’ s law (1852)
The Science and History of Ultraviolet Light

7. The Science and History of Ultraviolet Light
In 1800, Fredrich William, was experimenting with
passing sunlight through a glass prism. He observed
that temperatures increased the more he went towards
the red end of the spectrum. As a scientist he
measured beyond the red end of the spectrum, naming
it “ultra-red.”

8. The rate of decrease of intensity (monochromatic light) with the
thickness of the medium is directly proportional to the intensity of
incident light
“Beer’s Law
(1852)
Lambert Law
(1760)
The intensity of a beam of monochromatic light decreases
exponentially with increase in the Concentration of absorbing
species arithmetically

9. Beer’s law (related to Concentration of absorbing species)
Lambert’s law (related to thickness/path length of absorbing
species)
These two laws are applicable under the following condition:
I = Ia + It
I = Intensity of incident light
Ia = Intensity of absorbed light
It = Intensity of transmitted light
Beer-Lambert Law: A ∝ c l
c = Concentration
l = path length

10. UVX-rays IRγ-rays RadioMicrowave
Visible
λ, nm
Violet 400-420
Indigo 420-440
Blue 440-490
Green 490-570
Yellow 570-585
Orange 585-620
Red 620-780
It cannot be seen by human eyes. The colour
spectrum of visible light goes ( increasing
frequency) from red to orange, then yellow,
green, blue, indigo then violet. As the
frequency of the light increases beyond the
violet,
Ultraviolet 200 to 400nm Visible
UV & Visible

11. reference
detector
I0
I0 I0
I
200
λ, nm
monochromatic/
beam splitter optics
UV-VIS sources
log(I0/I) = A
700
sample
Monochromatic Light
monochromatic light is light made of one colour.it is coming from the word
mono,which means one.
Lambda max is the wavelength at which the maximum fraction of light is
absorbed by a solution. Lambda (λ) is a Greek letter that scientists use as the
symbol for wavelength.
λ max
Cells can be made of plastic, glass or quartz

12. Spectrophotometery
Transmittance
Absorbance
Beer-Lambert Law: A ∝ l c

13. Deuterium lamp
Deuterium lamps are light Sources that utilize the discharge
of excited deuterium gas (D2).
They emit a continuum of UV light with in the wavelength
range 185-400nm
Widely used as ultraviolet source in analytical equipment,
such as UV-Vis spectrophotometers and HPLC instruments.
Deuterium lamps highest stability, intensity – more than 2,000
hours.
Tungsten Halogen lamps (TH) generate a continuous spectrum
between 350-3000nm.
Tungsten Halogen lamp
Source of UV-Vis light

14. Working & Handling of

17. Thanks for ALL

18. gmail & face book: n.seshadris@gmail.com