Lecture 19

1. Lecture 19 Spectrophotometry-III

2. Monochromator (filter, wavelength selector) Light Source Detector Sample Spectrometer Data Processing

3. Single beam Double beam

4. A tungsten lamp 3000 K

5. UV sources Deuterium Lamp Deuterium: higher intensity

6. Incident light Emergent light Limits to Beer’s Law P1 P0 Stray light

8. Solvents for UV/vis Spectrophotometry Solvent Lower Wavelength Limit Water 180 nm Ethanol 220 nm Hexane and 200 nm Cyclohexane Acetone 320 nm

10. Bugert, Lambert and Beer Beer’s law A Straight line! concentration

11. A or  Measure @ this wavelength! Other components of the mixture B Wavelength, nm

12. Limits to Beer’s Law Polychromatic light (several wavelength)

13. A or  Other components of the mixture Intensity is too low! B Wavelength, nm

14. A or  Other components of the mixture B Measurement is difficult Wavelength, nm

15. A or  Measure @ this wavelength! Other components of the mixture C B + reagent  C Compound is chemically derivitized (transformed) prior to the measurement of absorbance Wavelength, nm

16. Cu2+ Hg2+