7. optical spectroscopy at cryogenic temperatures
DESCRIPTION
7. Optical Spectroscopy at Cryogenic Temperatures. Zero-Phonon Line: transition without creation or destruction of phonons Phonon Wing: at T = 0 K, creation of one or more phonons. Mirror Image. Absorption and fluorescence spectra are related by a mirror symmetry around the 0-0 transition. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/1.jpg)
• Zero-Phonon Line: transition without creation or destruction of phonons
• Phonon Wing: at T = 0 K, creation of one or more phonons
7. Optical Spectroscopy at Cryogenic Temperatures
![Page 2: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/2.jpg)
Mirror Image
Absorption and fluorescence spectra are related by a mirror symmetry around the 0-0 transition
![Page 3: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/3.jpg)
Intensity and Width of ZPL
• Intensity decreases steeply with T
• Width limited by excited-state lifetime and dephasing (thermal fluctuations)
1
22
tanhexpTk
IB
ZPL
*21
hom21
TT
![Page 4: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/4.jpg)
Inhomogeneous Broadening
Disorder and defects cause a spread ofelectronic transition frequencies
![Page 5: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/5.jpg)
Single-Molecule Spectroscopy
Spectral selection of single molecules
![Page 6: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/6.jpg)
The first optical detection of a single molecule, via absorption (W. E. Moerner and L. Kador, Phys. Rev. Lett. 62 (1989) 2535)
Detection of single molecules by fluorescence excitation (M. Orrit and J. Bernard, Phys. Rev. Lett. 65 (1990) 2716)
![Page 7: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/7.jpg)
8. Two-Level System in a Laser Field
• Detuning from resonance• Rabi frequency
0Eeg
eg
![Page 8: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/8.jpg)
Optical Saturation
Saturation of the fluorescence excitationline of a single dibenzoterrylene moleculein a naphthalene crystal
Maximum intensity and width as functions of the laser power
![Page 9: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/9.jpg)
Transients: Optical Nutation
Nutation transients without (left) and with (right) coherence damping
![Page 10: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/10.jpg)
Antibunching histograms
Antibunching at low temperature (left, pentacene in p-terphenyl) and at room temperature (right, terrylene in p-terphenyl)
![Page 11: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/11.jpg)
Quantum Optics
Light Shift of the optical transition
Correlation histogramsof a single-photon source
![Page 12: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/12.jpg)
9. Triplet State(s)• Only one triplet level: correlation function
• Two sublevels:
311331
13)2( 1)( kkekkg
212
212
2313
12 TTTTkk
![Page 13: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/13.jpg)
On- and Off-time Statistics
From: Th. Basché, S. Kummer, Ch. Bräuchle, Nature 373 (1995) 132
![Page 14: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/14.jpg)
Optically Detected Magnetic Resonance• Microwave transfers populations between triplet sublevels, modifying the average fluorescence intensity
• … here for a pentacene molecule in a p-terphenyl crystal,
![Page 15: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/15.jpg)
• … or changing the off-time statistics,
• here for terrylene in p-terphenyl, A. C. J. Brouwer et al., Phys. Rev. Lett. 80 (1998) 3944.
![Page 16: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/16.jpg)
Single nuclear spins
ODMR of fully deuterated single pentacene molecules containing only C12 atoms (left), or one C13 atom in two different positions (center, right). The splitting is due to the nuclear spin J. Köhler et al., Science 268, 1995,1457.
![Page 17: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/17.jpg)
10. External Fields• Stark effect
• quadratic …or linear.
EEEh�
21
![Page 18: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/18.jpg)
Shift of single terrylene molecule lines under modification of the carrier gas in a semiconductor (ITO) by an applied sawtooth voltage
![Page 19: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/19.jpg)
Low-frequency localized acoustic modes
![Page 20: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/20.jpg)
11. Spectral Diffusion• Jumps or drift of the ZPL in spectrum• Two-level Systems in Glasses
Evidence for a singleTLS in the correlationof a terrylene moleculein polyethylene
![Page 21: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/21.jpg)
Spectral jumps in p-terphenyl crystals
a: p-terphenyl
b: terrylene
Crystal structure 4 spectroscopic sites of terrylenein p-terphenyl
![Page 22: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/22.jpg)
Spectral diffusion close to domain walls
W. P. Ambrose et al.J. Chem. Phys. 95(1991) 7150.
• Wall = 2D lattice of 2-level systems• Random jumps spectral diffusion
![Page 23: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/23.jpg)
12. Interacting Single Molecules• Contact interactions• Electron exchange
• Dipole-dipole coupling
3
0
2
4 rJ
leads to ¨FRET, excitonic coupling
![Page 24: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/24.jpg)
Exciton coupling in a dimer
BA sincos1
BA cossin2
Jtg 2
22 J
Energies
![Page 25: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/25.jpg)
Bacterial Light-Harvesting Complex
B800 ring
B850 ring
![Page 26: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/26.jpg)
Excitation spectra of single LH2’s
Ensemble
Individual Complexes
A. van Oijen et al., Science 285 (1999) 400.
![Page 27: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/27.jpg)
Exciton coupling in the B850 ringk=0 excitonk= ± 1 excitons
split by distortion
![Page 28: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/28.jpg)
Two Quasi-Resonant Molecules
• A new two-photon resonance appears at high laser intensity between two single-molecule lines
C. Hettich et al., Science 298 (2002) 386.
![Page 29: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/29.jpg)
Two-photon resonance
Excitation of Molecule 1
Excitation of Molecule 2
Molecules are coupled!
![Page 30: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/30.jpg)
13. Other Single Molecule Experiments
• Studies of soft matter and materials• Other emitters, SC nanocrystals, color centers• Blinking statistics
• Non-fluo. optical detection methods• Photothermal detection• Pump-probe and other nonlinear spectroscopies
![Page 31: 7. Optical Spectroscopy at Cryogenic Temperatures](https://reader036.vdocuments.us/reader036/viewer/2022062500/56815a69550346895dc7bc06/html5/thumbnails/31.jpg)
Conclusion
• SM Microscopy at room T:– biophysics– material science
• SM Spectroscopy at room and low T: – molecular physics– quantum optics– solid state physics