1. Lecture 6 Radiative Transition in Atoms, Molecules & Insulators/Semiconductors
Read: FQ 4, FS 3

2. Textbook 1: M. Fox “Optical Properties of Solids” (2nd ed, Oxford)
We’ll cover a good portion of FS
+ selected modern topics
Online pdf (1st ed) seems to be available (google)

3. Textbook 2: M. Fox “Quantum Optics” (Oxford)
“FQ”
We’ll cover part of FQ+suppl topics
Available online from Purdue Library Website

4. Now move on to quantum (semiclassical)
molecule

5. Semiclassical Light-Matter interaction: Einstein Coefficients
(FQ Ch4/FS App-B)
(Planck blackbody)

6. Radiative Transition Rates
Fermi Golden Rule
(DOS of final state: light (photon) +matter [neglect if discrete])
X-polarized:

7. Selection Rules (even/odd) (orbital)
Question: when will spin change (delta ms) be allowed? [SOC? Magnetic, NMR? ]

8. Transition matrix element
Fluorescence
phosphorescence
“forbidden” transition
Metastable state

9. Also can engineer DOS g to control transition rates!
cavity
Photonic crystal (bandgap)/
Metamaterials …

10. Molecules & molecular solids

11. Jablonski Diagram
Singlet
SO coupling
Triplet
Singlet

12. (3) 1Σ
(2) 3Σ
(2) 1Σ
LIF
(1) 3Σ
excitation
(X) 1Σ

13. Molecular Spectroscopy in a heat-pipe (7Li85Rb)
Cooling water
Cooling water
Heaters
Laser
LIF Rb
300 ̊C Li
550 ̊C Rb
300 ̊C
λ-meter
PMT
Monochromator
LIF
(A) Laser Induced Fluorescence (LIF)
Laser
(B) Excitation Spectroscopy

14. Laser Induced Fluorescence (LIF)
From low v’ levels of B 1Π state
Korek et al.,
Chem Phys 256 1
Dutta et al., Chem Phys Lett (2011),
doi: /j.cplett

15. Fluorescence from successively higher vib. (1) 1П statesP R P R

16. Franck-Condon Overlap of Vibronic state

17. Photo-association
laser

18. PA rate of 7Li near FR M.Junker et al., PRL 2008 a > 0 a < 0
I = 1.65 W/cm2
v’’ = 83
T ~ 10 mK
~104
a > 0
a < 0
v’’ = 84
v’’ = 83
v’’ = 82
M.Junker et al.,
PRL 2008

19. Why the zero?
Rate depends on ground state wavefunction (Franck-Condon)
2S1/2 + 2P1/2 r
v’’ Rc
big
f(Rc) R~ 2 E
2S1/2 + 2S1/2
small r
Bohn and Julienne PRA 60, 414 (1999).