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Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
Uv – Visible Spectrophotometer.HARIS
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Uv – Visible Spectrophotometer.HARIS

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  • 1. UV - VISIBLE SPECTROPHOTOMETER HARIS P
  • 2. Spectrophotometer <ul><li>• Measures the light that passes through a liquid sample </li></ul><ul><li>• Spectrophotometer gives readings in Percent Transmittance (%T) and in Absorbance (A) </li></ul>
  • 3. The Electromagnetic Spectrum  = c /  E = h 
  • 4. Absorbance and Complementary Colors
  • 5. I o I Cell with Pathlength, b, containing solution light source detector blank where I o = I concentration 2 concentration 1 b with sample I < I o The process of light being absorbed by a solution As concentration increased, less light was transmitted (more light absorbed).
  • 6. <ul><li>The law states that the amount of light absorbed by a solution (colored) is proportional to the concentration of the absorbing substance and to the thickness of the absorbing material (path length). Absorbance is also called optical density </li></ul><ul><li>A = abc </li></ul><ul><li>where a – molar absorptivity, b – pathlength, and c – molar concentration </li></ul>BEER - LAMBERT'S LAW
  • 7. Some terminology <ul><li>I – intensity where I o is initial intensity </li></ul><ul><li>T – transmission or %T = 100 x T </li></ul><ul><li>(absorption: Abs = 1 – T or %Abs = 100 - %T) </li></ul><ul><li>T = I/ I o </li></ul><ul><li>A – absorbance </li></ul><ul><li>A = - log T = -log I/ I o </li></ul>
  • 8. <ul><li>The blank contains all substances expect the analyte. </li></ul><ul><li>Is used to set the absorbance to zero: </li></ul><ul><li>A blank = 0 </li></ul><ul><li>This removes any absorption of light due to these substances and the cell. </li></ul><ul><li>All measured absorbance is due to analyte. </li></ul>The Blank
  • 9. Conventional Spectrophotometer 1. A stable and cheap energy source. 2. A monochromator to break the polychromatic radiation into component and wavelength/bands of wave length. 3. Transparent vessels (cuvettes) to hold the sample. 4. A photo sensitive detector and associated amplifier and recorder
  • 10. Conventional Spectrophotometer Optical system of a split-beam spectrophotometer
  • 11. LIGHT SOURCES   UV Spectrophotometer 1. Hydrogen Gas Lamp 2. Mercury Lamp Visible Spectrophotometer 1. Tungsten Lamp IR Spectrophotometer 1. Carborundum (SIC)
  • 12. Light Source <ul><li>Deuterium Arc Lamp </li></ul><ul><li> UV Region </li></ul><ul><li>Wavelength Range : </li></ul><ul><li>190~420nm </li></ul><ul><li>Tungsten Lamp </li></ul><ul><li> Wavelength Range : Part of the UV and the whole of the Visible </li></ul><ul><li>range ( 약 350 ~ 2,500nm) </li></ul><ul><li>Xenon Lamp </li></ul><ul><li> Wavelength Range : 190~800nm </li></ul>
  • 13. Monochromator <ul><li>Accepts polychromatic input light from a lamp and outputs monochromatic light </li></ul><ul><li>Components : Entrance slit, Dispersion device, Exit slit. </li></ul><ul><li>The resolving element are of two kinds namely, </li></ul><ul><li>prisms and diffraction gratings. Simple glass prisms are used for visible range. For UV region silica, fused silica or quartz prism is used. Fluorite is used in vaccum UV range. </li></ul><ul><li>Gratings are often used in the monochromators of spectrophotometers operating in UV, visible and infra red regions. Their resolving power is far superior to that of prisms & they yield a linear resolution of spectrum. </li></ul>
  • 14. Dispersion Devices <ul><li>Non-linear dispersion </li></ul><ul><li>Temperature sensitive </li></ul><ul><li>Linear Dispersion </li></ul><ul><li>Different orders </li></ul>
  • 15. CELLS UV Spectrophotometer Quartz (crystalline silica)   Visible Spectrophotometer Glass   IR Spectrophotometer NaCl
  • 16. Cell Types I Open-topped rectangular standard cell (a) and apertured cell (b) for limited sample volume
  • 17. Cell Types II Micro cell (a) for very small volumes and flow-through cell (b) for automated applications
  • 18. Detection Devices <ul><li>Most detectors depend on the photoelectric effect, where incident light photons) liberates electrons from a metal or other material surface. </li></ul><ul><li>Important requirements for a detector </li></ul><ul><li>(1)high sensitivity to allow the detection of low levels of radiant energy, </li></ul><ul><li>(2)short response time, </li></ul><ul><li>(3)long term stability, and </li></ul><ul><li>(4)an electronic signal which is easily amplified for typical read out apparatus, Ultraviolet and visible radiation detectors are photocells, phototubes and photo multiplier tubes. </li></ul>
  • 19. Photomultiplier Tube Detector Anode <ul><li>High sensitivity at </li></ul><ul><li>low light levels </li></ul><ul><li>Cathode material </li></ul><ul><li>determines spectral sensitivity </li></ul><ul><li>Good signal/noise </li></ul><ul><li>Shock sensitive </li></ul>
  • 20. Amplification and Readout <ul><li>Radiation detectors generate electronic signals which are proportional to the transmitter light. </li></ul><ul><li>These signals need to be translated to a form that is easy to interpret. </li></ul><ul><li>This is accomplished by using amplifiers, ammeters, potentiometers, and potentiometric recorders. </li></ul>
  • 21. <ul><li>1. Qualitative Analysis </li></ul><ul><li>2. Quantitative Analysis </li></ul><ul><li>3. Molecular weight determination </li></ul><ul><li>4. Study of cis-trans Isomerism </li></ul><ul><li>5. Other Physiochemical studies </li></ul><ul><li>6. Control of Purification </li></ul><ul><li>7. Difference Spectroscopy </li></ul><ul><li>8. Turbidimetry </li></ul>Applications of UV - Visible Spectroscopy
  • 22. <ul><li>Thank You </li></ul>

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