Lecture 30 11/14/05. Spectrophotometry Properties of Light h = 6.626 x 10 -34 J-s c = 3.00 x 10 8 m/s.

Presentation on theme: "Lecture 30 11/14/05. Spectrophotometry Properties of Light h = 6.626 x 10 -34 J-s c = 3.00 x 10 8 m/s."— Presentation transcript:

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

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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

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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

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22 IC: Internal conversion ISC: Intersystem crossing

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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] +....

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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

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

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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

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40 IC: Internal conversion ISC: Intersystem crossing

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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] +....

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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

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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

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58 IC: Internal conversion ISC: Intersystem crossing

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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] +....

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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

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

68 `