1. Lecture 30 11/14/05

2. Spectrophotometry

3. Properties of Light h = 6.626 x 10 -34 J-s c = 3.00 x 10 8 m/s

6.  Transmittance  Absorbance P = Irradiance (Intensity) = energy per second per area of light

7. Beer’s Law A=  bc  = extinction coefficient or molar absorptivity b = pathlength c = concentration

15. Recap  Absorbance Specific wavelengths of light electronic transition UV/Vis: electronic transition Vibrations IR: Vibrations  Beer’s Law For Quantitation

16. Beer’s Law  Monochromatic light  Dilute solutions

17. IC: Internal conversion ISC: Intersystem crossing

18. Luminescence  Fluorescence Emission of photon during transition between S 1  S 0  Phosphorescence Emission of photon during transition between T 1  S 0

19. Luminescence  More sensitive than absorption  Lower energy (higher wavelength) than the energy absorbed

22. IC: Internal conversion ISC: Intersystem crossing

25. I = kP 0 c

26.  Excitation spectrum vs. emission spectrum

27. Analysis of a Mixture  A =  X b[X] +  Y b[Y] +  Z b[Z] +....

29. Spectra overlap 1.Constant concentration of both analytes 1. Find  at different 2.Least squares to find best values of [X] and [Y] 1. A m =  X b[X] +  Y b[Y] 2. A calc =  X b[X] guess +  Y b[Y] guess

31. Spectra not-overlapping A’ =  ’ X b[X] +  ’ Y b[Y] at ’ A’’ =  ’’ X b[X] +  ’’ Y b[Y] at ’’

32. `

33. Recap  Absorbance Specific wavelengths of light electronic transition UV/Vis: electronic transition Vibrations IR: Vibrations  Beer’s Law For Quantitation

34. Beer’s Law  Monochromatic light  Dilute solutions

35. IC: Internal conversion ISC: Intersystem crossing

36. Luminescence  Fluorescence Emission of photon during transition between S 1  S 0  Phosphorescence Emission of photon during transition between T 1  S 0

37. Luminescence  More sensitive than absorption  Lower energy (higher wavelength) than the energy absorbed

40. IC: Internal conversion ISC: Intersystem crossing

43. I = kP 0 c

44.  Excitation spectrum vs. emission spectrum

45. Analysis of a Mixture  A =  X b[X] +  Y b[Y] +  Z b[Z] +....

47. Spectra overlap 1.Constant concentration of both analytes 1. Find  at different 2.Least squares to find best values of [X] and [Y] 1. A m =  X b[X] +  Y b[Y] 2. A calc =  X b[X] guess +  Y b[Y] guess

49. Spectra not-overlapping A’ =  ’ X b[X] +  ’ Y b[Y] at ’ A’’ =  ’’ X b[X] +  ’’ Y b[Y] at ’’

50. `

51. Recap  Absorbance Specific wavelengths of light electronic transition UV/Vis: electronic transition Vibrations IR: Vibrations  Beer’s Law For Quantitation

52. Beer’s Law  Monochromatic light  Dilute solutions

53. IC: Internal conversion ISC: Intersystem crossing

54. Luminescence  Fluorescence Emission of photon during transition between S 1  S 0  Phosphorescence Emission of photon during transition between T 1  S 0

55. Luminescence  More sensitive than absorption  Lower energy (higher wavelength) than the energy absorbed

58. IC: Internal conversion ISC: Intersystem crossing

61. I = kP 0 c

62.  Excitation spectrum vs. emission spectrum

63. Analysis of a Mixture  A =  X b[X] +  Y b[Y] +  Z b[Z] +....

65. Spectra overlap 1.Constant concentration of both analytes 1. Find  at different 2.Least squares to find best values of [X] and [Y] 1. A m =  X b[X] +  Y b[Y] 2. A calc =  X b[X] guess +  Y b[Y] guess

67. Spectra not-overlapping A’ =  ’ X b[X] +  ’ Y b[Y] at ’ A’’ =  ’’ X b[X] +  ’’ Y b[Y] at ’’

68. `