1. Long-Lived Dilute Photocarriers in Individualy-suspended Single-Walled Carbon Nanotubes Y. Hashimoto, A. Srivastava, J. Shaver, G. N. Ostojic, S. Zaric, V. C. Moore, R. H. Hauge, R. E. Smalley, and J. Kono Rice University Out line Introduction & Purpose Sample and Experimental setup Results and discussion Photo-induced carrier dynamics Polarization memory Summary Longer than 1 nano-second !!! Supported by TATP and Welch Foundation

2. ultimate quantum wire Introduction to Single-Walled Carbon Nanotube Diameter: 1 nano-meter Length: < 1 inch peak (n,m) Each peak corresponds to particular (n,m)

3. Single Walled Carbon Nanotubes photo-induced carrier life time Hertel and Moos, Phys. Rev. Lett. 84, 5002 (2000) Chen et al., Appl. Phys. Lett. 81, 975 (2002) Han et al., Appl. Phys. Lett. 82, 1458 (2003) Lauret et al., Phys. Rev. Lett. 90, 057404 (2003) Korovyanko et al. Phys. Rev. Lett. 92, 017403 (2004) < 1 ps Bundled SWNT 5 - 50 ps Isolated SWNT G. N. Ostojic et al., Phys. Rev. Lett. 92, 117402 (2004) Y.-Z. Ma et al., J. Chem. Phys. 120, 3368 (2004) A. Hagen et al., Appl. Phys. A 78, 1137 (2004) F. Wang et al., Phys. Rev. Lett. 92, 177401 (2004) ~ 20 ns Theoretical C. D. Spataru et al., cond-mat/0301220 v1 (2003) ~ ns Isolated SWNT This work

4. Purpose Photo-induced carrier relaxation dynamics in the low excitation limit Transient absorption  ~ 10 ps 1 – 30 mJ/cm 2 (0.89eV) Phys. Rev. Lett. 92, 117402 (2004) 0.06 – 5.7 mJ/cm 2 J. Chem. Phys. 120, 3368 (2004) Time resolved fluence  ~ 7 ps 0.002 mJ/cm 2 Estimate the radiatibe relaxation time as 110 ns Phys. Rev. Lett. 92, 177401 (2004)  ~ 10 ps 1 – 30 mJ/cm 2 (0.89eV) G. N. Ostojic et al., Phys. Rev. Lett. 92, 117402 (2004)  ~ 0.06 – 5.7 mJ/cm 2 Y.-Z. Ma et al., J. Chem. Phys. 120, 3368 (2004) A. Hagen et al., Appl. Phys. A 78, 1137 (2004)  ~ 7 ps 0.002 mJ/cm 2 F. Wang et al., Phys. Rev. Lett. 92, 177401 (2004) The relaxation dynamics of the photo-excited carriers in SWNTs radiativeNon-radiative ~ ps ~ ns Tube-tube interaction Catalyst particles at the tube ends Nonradiative recombination via surface defects etc. Exciton-exciton interaction ? What kind of the Non-radiative relaxation is taken place ? ~1mJ/cm2 ~640 e-h pairs in 1  m SWNT PRL. 92, 077402 (2004) In the previous study with a high-peak power OPA laser  < 20 ps 1 e-h pair per 1  m SWNT

5. Absorption shows sharp peaks SWNT is well isolated Single Walled Carbon Nanotube Sample Absorption spectrum Excited SWNTs are (12,5), (12,1), (11,3) (10,5), (9,8), (9,7) Raman spectrum SWNT SDS micelle SDS miscelled SWNT Science VOL 297 593 (2002)

6. Experimental setup / 2 Pulse picker 80 MHz – 800 kHz Ti:s laser 80MHz Excitation fluence: 100 nJ/cm 2 Pump : Probe = 10 : 1 Si detector Lock in Laser wavelength: 1.550 eV (E2H2) Delay stage (2 ns) Aperture SWNT

7. Photo-induced carrier dynamics in SWNT in low excitation limit Pump and probe signal persist even at 1 nano-second Photo-induced carrier dynamics shows very long decay !!! Room temperature Repetition rate: 8 MHz Polarization of the pump and probe: Previous report in high excitation  ~ 20 ps

8. 1:  < 1 ps 2:  ~ 1 ns Decay dynamics

9. E E1 DOS E2 H2 H1 Decay dynamics ~ ns E2H2  E1H1 intraband transition E1H1 carrier recombination < 1 ps

10. Polarization memory Polarization memory persist even at 1 ns !!! In bundled SWNT, the polarization decay time ~ 10 ps O. J. Korovyanko et al., Phys. Rev. Lett. 92 017403 (2004) Polarization of the pump and probe pulses

11. Summary The transient absorption of the isolated SWNTs in low excitation regime shows very fast (< 1 ps) E2H2  E1H1 intraband transition and very long (~ 1ns) E1H1 carrier recombination Future work Two color pump-probe in the isolated SWNT in the low excitation limit The polarization memory in isolated SWNTs shows no decay even at 1 ns.

12. Excited SWNT (12,1)L : 797 nm (11,3)L : 792 nm (10,5)l : 786 nm (9,7)l : 790 nm Raman spectrum

13. How to estimate the carrier concentration Density of the SWNT in solution:~20 x 10 -6 g/cm 3 Mass density of SWNT (11. 0): 2.06 x 10 -18 g/  m Density of the SWNT: 9.7 x 10 11  m/cm  (in the 1mm path length cuvette) Excitation intensity:1 mJ/cm 2 Photon energy:1 eV Excitation intensity: 6.2 x 10 15 photon/cm 2 Absorption:10% (per 1 mm)

15. Long-Lived Dilute Photocarriers in Individualy-suspended Single-Walled Carbon Nanotubes Y. Hashimoto, A. Srivastava, J. Shaver, G. N. Ostojic, S. Zaric, V. C. Moore, R. H. Hauge, R. E. Smalley, and J. Kono Rice University Out line Introduction & Purpose Sample and Experimental setup Results and discussion Photo-induced carrier dynamics Polarization memory Summary Longer than 1 nano-second !!! Supported by TATP and Welch Foundation

16. ultimate quantum wire Introduction to Single-Walled Carbon Nanotube Diameter: 1 nano-meter Length: < 1 inch

17. Single Walled Carbon Nanotubes photo-induced carrier life time Hertel and Moos, Phys. Rev. Lett. 84, 5002 (2000) Chen et al., Appl. Phys. Lett. 81, 975 (2002) Han et al., Appl. Phys. Lett. 82, 1458 (2003) Lauret et al., Phys. Rev. Lett. 90, 057404 (2003) Korovyanko et al. Phys. Rev. Lett. 92, 017403 (2004) < 1 ps Bundled SWNT 5 - 50 ps Isolated SWNT G. N. Ostojic et al., Phys. Rev. Lett. 92, 117402 (2004) Y.-Z. Ma et al., J. Chem. Phys. 120, 3368 (2004) A. Hagen et al., Appl. Phys. A 78, 1137 (2004) F. Wang et al., Phys. Rev. Lett. 92, 177401 (2004) ~ 20 ns Theoretical C. D. Spataru et al., cond-mat/0301220 v1 (2003) ~ ns Isolated SWNT This work

18. Purpose Photo-induced carrier relaxation dynamics in the low excitation limit Transient absorption  ~ 10 ps 1 – 30 mJ/cm 2 (0.89eV) Phys. Rev. Lett. 92, 117402 (2004) 0.06 – 5.7 mJ/cm 2 J. Chem. Phys. 120, 3368 (2004) Time resolved fluence  ~ 7 ps 0.002 mJ/cm 2 Estimate the radiatibe relaxation time as 110 ns Phys. Rev. Lett. 92, 177401 (2004)  ~ 10 ps 1 – 30 mJ/cm 2 (0.89eV) G. N. Ostojic et al., Phys. Rev. Lett. 92, 117402 (2004)  ~ 0.06 – 5.7 mJ/cm 2 Y.-Z. Ma et al., J. Chem. Phys. 120, 3368 (2004) A. Hagen et al., Appl. Phys. A 78, 1137 (2004)  ~ 7 ps 0.002 mJ/cm 2 F. Wang et al., Phys. Rev. Lett. 92, 177401 (2004) The relaxation dynamics of the photo-excited carriers in SWNTs radiativeNon-radiative ~ ps ~ ns Tube-tube interaction Catalyst particles at the tube ends Nonradiative recombination via surface defects etc. Exciton-exciton interaction ? What kind of the Non-radiative relaxation is taken place ? ~1mJ/cm2 ~640 e-h pairs in 1  m SWNT PRL. 92, 077402 (2004) In the previous study with a high-peak power OPA laser  < 20 ps 1 e-h pair per 1  m SWNT

19. Absorption shows sharp peaks SWNT is well isolated Single Walled Carbon Nanotube Sample Absorption spectrum Excited SWNTs are (12,5), (12,1), (11,3) (10,5), (9,8), (9,7) Raman spectrum SWNT SDS micelle SDS miscelled SWNT Science VOL 297 593 (2002)

20. Experimental setup / 2 Pulse picker 80 MHz – 800 kHz Ti:s laser 80MHz Excitation fluence: 100 nJ/cm 2 Pump : Probe = 10 : 1 Si detector Lock in Laser wavelength: 1.550 eV (E2H2) Delay stage (2 ns) Aperture SWNT

21. Photo-induced carrier dynamics in SWNT in low excitation limit Pump and probe signal persist even at 1 nano-second Photo-induced carrier dynamics shows very long decay !!! Room temperature Repetition rate: 8 MHz Polarization of the pump and probe: Previous report in high excitation  ~ 20 ps

22. 1:  < 1 ps 2:  ~ 1 ns Decay dynamics

23. E E1 DOS E2 H2 H1 Decay dynamics ~ ns E2H2  E1H1 intraband transition E1H1 carrier recombination < 1 ps

24. Polarization memory Polarization memory persist even at 1 ns !!! In bundled SWNT, the polarization decay time ~ 10 ps O. J. Korovyanko et al., Phys. Rev. Lett. 92 017403 (2004) Polarization of the pump and probe pulses

25. Summary The transient absorption of the isolated SWNTs in low excitation regime shows very fast (< 1 ps) E2H2  E1H1 intraband transition and very long (~ 1ns) E1H1 carrier recombination Future work Two color pump-probe in the isolated SWNT in the low excitation limit The polarization memory in isolated SWNTs shows no decay even at 1 ns.