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Title: 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

Abstract

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 processmore » 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.« less

Authors:
; ;
Publication Date:
Research Org.:
Emory Univ., Atlanta, GA (US)
Sponsoring Org.:
USDOE; Petroleum Research Fund
OSTI Identifier:
20075900
DOE Contract Number:  
FG02-98ER14918
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory
Additional Journal Information:
Journal Volume: 104; Journal Issue: 18; Other Information: PBD: 11 May 2000; Journal ID: ISSN 1089-5639
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 14 SOLAR ENERGY; RHENIUM COMPLEXES; TITANIUM OXIDES; ZIRCONIUM OXIDES; EXCITED STATES; DYNAMICS; THIN FILMS; SOLUTIONS; CARBONYLS

Citation Formats

Wang, Y., Asbury, J.B., and Lian, T. 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. United States: N. p., 2000. Web. doi:10.1021/jp9936648.
Wang, Y., Asbury, J.B., & Lian, T. 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. United States. doi:10.1021/jp9936648.
Wang, Y., Asbury, J.B., and Lian, T. Thu . "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". United States. doi:10.1021/jp9936648.
@article{osti_20075900,
title = {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},
author = {Wang, Y. and Asbury, J.B. and Lian, T.},
abstractNote = {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.},
doi = {10.1021/jp9936648},
journal = {Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory},
issn = {1089-5639},
number = 18,
volume = 104,
place = {United States},
year = {2000},
month = {5}
}