Ultrafast excited-state dynamics of Re(CO){sub 3}Cl(dcbpy) in solution and on nanocrystalline TiO{sub 2} and ZrO{sub 2} thin films
Femtosecond infrared spectroscopy was used to study the excited-state dynamics of Re(CO){sub 3}Cl(dcbpy) in DMF solution and on the surface of ZrO{sub 2} and TiO{sub 2} nanocrystalline thin films. For Re(CO){sub 3}Cl(dcbpy) in DMF solution, the authors observed a long-lived {sup 3}MLCT state with a lifetime of >1 ns. The frequencies for the CO stretching bands were blue-shifted compared to those in the ground state, consistent with the metal-to-ligand charge-transfer nature of the excited state. Rapid spectral evolution of the excited-state CO stretching bands was observed within the first 12 ps. For Re(CO){sub 3}Cl(dcbpy) on ZrO{sub 2} thin films, a similar {sup 3}MLCT state was observed. However, the spectral blue shift was much less pronounced and occurred on a faster time scale. The authors suggest that vibrational relaxation is the primary contribution to the spectral evolution of Re(CO){sub 3}Cl-(dcbpy) on the ZrO{sub 2} film, whereas both vibrational relaxation and solvation of the MLCT state contribute to the spectral evolution in DMF solution. The excited-state decay rate of Re(CO){sub 3}Cl(dcbpy) on ZrO{sub 2} films was faster than the rate in DMF and increased with higher excitation power. The faster excited-state decay is attributed to the occurrence of an excited-state quenching process between neighboring excited molecules on the film. For Re(CO){sub 3}Cl(dcbpy)-sensitized TiO{sub 2} thin films, broad mid-IR absorption of injected electrons was observed. The rise time of the electron absorption signal in TiO{sub 2} was found to be less than 100 fs. In addition, the adsorbate CO stretching bands were also observed. The detailed information about the electron-injection process that can be obtained from the adsorbate vibrational spectra is discussed.
- Research Organization:
- Emory Univ., Atlanta, GA (US)
- Sponsoring Organization:
- USDOE; Petroleum Research Fund
- DOE Contract Number:
- FG02-98ER14918
- OSTI ID:
- 20075900
- Journal Information:
- Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Vol. 104, Issue 18; Other Information: PBD: 11 May 2000; ISSN 1089-5639
- Country of Publication:
- United States
- Language:
- English
Similar Records
Multiple-exponential electron injection in Ru(dcbpy){sub 2}(SCN){sub 2} sensitized ZnO nanocrystalline thin films
Ultrafast interligand electron transfer in cis -[Ru(4,4′-dicarboxylate-2,2′-bipyridine) 2 (NCS) 2 ] 4− and implications for electron injection limitations in dye sensitized solar cells