Presentation_UV
Download as PPT, PDF1 like482 views
The document discusses the history and science of ultraviolet light and spectrophotometry. It covers: 1. The origins of ultraviolet light being discovered beyond the red end of the visible light spectrum in 1800. 2. Beer's law from 1852 relating the absorption of light to concentration of absorbing materials and Lambert's law relating absorption to path length. 3. How spectrophotometry uses monochromatic light from sources like deuterium and tungsten halogen lamps to measure the transmittance and absorbance of samples, following the Beer-Lambert law.
Presentation_UV
- 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
- 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