Παρουσίαση με θέμα: ""— Μεταγράφημα παρουσίασης:

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3 The classical picture is that the incident radiation excites dipolar oscillations in a polarisable system such as a molecule or atom which can act as secondary sources of EM radiation Harry Kroto 2004

4 P = E E = Eocos2πωt P = Eocos2πωt 4

5 this shows a Hertz osci http://en. wikipedia. org/wiki/File:Dipole
this shows a Hertz osci -oli Harry Kroto 2004 5

6 P = αo Eo cos 2πωet + ½(∂α/∂q) qo Eo[cos 2π(ωe+ ωq)t + cos 2π(ωe- ωq)t]
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7 P = αo Eo cos 2πωet + ½(∂α/∂q) qo Eo[cos 2π(ωe+ ωq)t + cos 2π(ωe- ωq)t]
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8 ½(∂α/∂q) qo Eo[cos 2π(ωe+ ωq)t]
P = αo Eo cos 2πωet + ½(∂α/∂q) qo Eo[cos 2π(ωe+ ωq)t + cos 2π(ωe- ωq)t] αo Eo cos 2πωet ½(∂α/∂q) qo Eo[cos 2π(ωe+ ωq)t] 8

9 ½(∂α/∂q) qo Eo[cos 2π(ωe+ ωq)t]
P = αo Eo cos 2πωet + ½(∂α/∂q) qo Eo[cos 2π(ωe+ ωq)t + cos 2π(ωe- ωq)t] αo Eo cos 2πωet ½(∂α/∂q) qo Eo[cos 2π(ωe+ ωq)t] ½(∂α/∂q) qo Eo[cos 2π(ωe- ωq)t] 9

10 ωe ω →

11 ωe ωe+ ωq ω → 11

12 ωe ωe- ωq ωe+ ωq ω → 12

13 ωe Stokes Line Anti-Stokes Line ωe- ωq ωe+ ωq ← ωq → ← ωq → ω → 13

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24 Harry Kroto 2004 24

25 P = E 25

26 P = E E = Eocos2πωt 26

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28 P = α E Total polarisability

29 P = α E Total polarisability
α = αo + (∂α/∂q)q Molecular polarisability - function of coordinate

30 P = α E Total polarisability
α = αo + (∂α/∂q)q Molecular polarisability - function of coordinate E = Eo cos 2πωet Electric Field radiation frequency ωe

31 P = α E Total polarisability
α = αo + (∂α/∂q)q Molecular polarisability - function of coordinate E = Eo cos 2πωet Electric Field radiation frequency ωe q = qo cos 2πωqt coordinate of the molecular motion ωq

32 P = α E Total polarisability
α = αo + (∂α/∂q)q Molecular polarisability - function of coordinate E = Eo cos 2πωet Electric Field radiation frequency ωe q = qo cos 2πωqt coordinate of the molecular motion ωq P = [αo + (∂α/∂q) q] E

33 P = α E Total polarisability
α = αo + (∂α/∂q)q Molecular polarisability - function of coordinate E = Eo cos 2πωet Electric Field radiation frequency ωe q = qo cos 2πωqt coordinate of the molecular motion ωq P = [αo + (∂α/∂q) q] E P = [αo + (∂α/∂q) q] Eo cos 2πωet

34 P = α E Total polarisability
α = αo + (∂α/∂q)q Molecular polarisability - function of coordinate E = Eo cos 2πωet Electric Field radiation frequency ωe q = qo cos 2πωqt coordinate of the molecular motion ωq P = [αo + (∂α/∂q) q] E P = [αo + (∂α/∂q) q] Eo cos 2πωet P = [αo + (∂α/∂q) qo cos 2πωqt] Eo cos 2πωet

35 P = α E Total polarisability
α = αo + (∂α/∂q)q Molecular polarisability - function of coordinate E = Eo cos 2πωet Electric Field radiation frequency ωe q = qo cos 2πωqt coordinate of the molecular motion ωq P = [αo + (∂α/∂q) q] E P = [αo + (∂α/∂q) q] Eo cos 2πωet P = [αo + (∂α/∂q) qo cos 2πωqt] Eo cos 2πωet P = αo Eo cos 2πωet + (∂α/∂q) qo Eocos 2πωqt cos 2πωet

36 P = α E Total polarisability
α = αo + (∂α/∂q)q Molecular polarisability - function of coordinate E = Eo cos 2πωet Electric Field radiation frequency ωe q = qo cos 2πωqt coordinate of the molecular motion ωq P = [αo + (∂α/∂q) q] E P = [αo + (∂α/∂q) q] Eo cos 2πωet P = [αo + (∂α/∂q) qo cos 2πωqt] Eo cos 2πωet P = αo Eo cos 2πωet + (∂α/∂q) qo Eocos 2πωqt cos 2πωet P = αo Eo cos 2πωet + ½(∂α/∂q) qo Eo[cos 2π(ωe+ ωq)t + cos 2π(ωe- ωq)t]

37 P = E E = Eocos2πωt P = Eocos2πωt 37

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39 P = E E = Eocos2πωt P = Eocos2πωt 39

40 P = E E = Eocosωt P = Eocosωt

41 Attenuation due to scattering by interstellar gas and dust clouds
Harry Kroto 2004

42 Harry Kroto 2004

43 Harry Kroto 2004

44 P =  E

45 P =  E

46 P =  E

47 P =  E

48 Bill Madden