1. Thick wedged films:

2. excitations in insulating
M.U. Gruninger,
1999
PhD Thesis
YBa2Cu3O6
Weakly absorbing
excitations in insulating
No absorbtive features in R(w)
Absorbtive features in T(w)

3. Plan parallel plates or films
source
detector

4. Optical Transmission

6. Thin films:
NbN
d=400 nm
9 K
13 K
18 K

9. SrTiO3 Sr
Transmission 10 20 30 40 50

11. Direct measurement of the polariton w(q) relation50
Transmission 10 20 30 40

13. THz time domain measurements
Fabry-Perot etalon
source
detector

14. THz time domain measurements
Fabry-Perot etalon
source
detector

15. THz transmission of SrTiO3
Time domain
intensity (a.u.) 31 32 33 34 35 36 37
delay line (mm)

16. THz transmission of SrTiO3
Time domain
Frequency domain
0.1
10-3
intensity (a.u.)
transmission
10-5 31 32 33 34 35 36 37 10 20 30 40 50
delay line (mm)
wavenumber (cm-1)
Fourier transformation

17. What do we measure with optics ?
Dipole transition from an
occuped state  to an emtpy state 

18. KCl s1(w) measures the interacting electron-hole spectral function
excitons
KCl
s(w)
Charge transfer gap
7.5
8.5
ħw (eV)

19. Field operator
Density operator
Density operator
Velocity operator

20. Interaction between light and matter Kubo formalism
Velocity operator:

22. In the limit of linear response this becomes
Finite temperature:

23. Finite temperature:
The two delta-functions cancel exactly !

24. Drude-Lorentz expansion

28. Al has 13 electrons/atom

29. Glover Tinkham Ferrell:
Optical conductivity
Bi2Sr2CaCu2O8
T=20 K
Tc=88K
T=300K
Glover Tinkham Ferrell:

30. Example, MgO:

32. f-sum rule
Free charge
spectral weight
(Kubo, 1957)

33. Electron Energy
Electron Momentum
Electron Energy

34. E//ab
Carbone, preprint ‘06
Molegraaf,Science’02

35. H.J.A.Molegraaf et al, Science 295, 2239 (2002)

36. Free charge
spectral weight
Nearest- neighbor
tight-binding approximation
Kinetic energy sum-rule

37. Calculated using BCS-model Molegraaf, Presura, vanderMarel, Kes, Li,
Science 295, (2002).
Loram, Luo, Cooper, Liang, Tallon,
J. Phys. Chem. Solids (2001).
Experiments

38. Special case: diatomic molecule
Hopping parameter: t

39.  
1 electron:

40. d
Hopping parameter: t
1 electron:

41. a’-NaV2O5 Topview: 4 V-atoms c average: V4.5+ 2 valence electrons
per unit cell c
Topview:
unit cell b a

42. b a t^
t^>> t||  

43. E ^ chain
E // chain