Ultrafast excited-state dynamics of ferrocene-bridge-acceptor system

Omar F. Mohammed; Abdelwareth A.O. Sarhan

doi:10.1016/j.chemphys.2010.04.014

Ultrafast excited-state dynamics of ferrocene-bridge-acceptor system

Omar F. Mohammed, Abdelwareth A.O. Sarhan

Research output: Contribution to journal › Article › peer-review

14 Scopus citations

Abstract

We employed both femtosecond fluorescence up-conversion and transient absorption techniques with ∼150 fs time resolution to study the excited-state deactivation process of an intra-molecular charge transfer model compound, 4-(ferrocen-1-yl)benzylidene-malononitrile (Fc-ph-DCV), which consists of ferrocene (Fc) unit as an electron donor, dicyanovinly (DCV) as an electron acceptor and phenyl (ph) ring as the central bridge. The results showed that after photoexcitation into the higher excited S₂ state, ultrafast internal conversion into S₁ takes place. The rate of S₂ → S₁ internal conversion is markedly faster (with a typical time of 120 fs ± 20 fs) than the diffusive solvation process. On the other hand, the lifetime of the relaxed S₁ state was strongly dependent on the solvent polarity, changing from 40 to 50 ps in acetonitrile to ∼20 ps in cyclohexane. Time-resolved fluorescence data also showed subpicosecond transient component that is attributable to the spectral relaxation caused by solvation and/or vibrational relaxation in the S₁ state.

Original language	English (US)
Pages (from-to)	17-21
Number of pages	5
Journal	Chemical Physics
Volume	372
Issue number	1-3
DOIs	https://doi.org/10.1016/j.chemphys.2010.04.014
State	Published - Jun 16 2010
Externally published	Yes

Bibliographical note

Funding Information:
We thank Professor Tahei Tahara and Dr. Satoshi Takeuchi for their assistance and useful discussions on the time-resolved experiments which have been done at RIKEN. We thank Japan Society for the Promotion of Science (JSPS) for providing a fellowship to Omar F. Mohammed. This work was also supported by chemistry department, Assiut University, Egypt.

Keywords

Charge transfer
Time-resolved fluorescence
Ultrafast internal conversion

ASJC Scopus subject areas

General Physics and Astronomy
Physical and Theoretical Chemistry

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10.1016/j.chemphys.2010.04.014

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title = "Ultrafast excited-state dynamics of ferrocene-bridge-acceptor system",

abstract = "We employed both femtosecond fluorescence up-conversion and transient absorption techniques with ∼150 fs time resolution to study the excited-state deactivation process of an intra-molecular charge transfer model compound, 4-(ferrocen-1-yl)benzylidene-malononitrile (Fc-ph-DCV), which consists of ferrocene (Fc) unit as an electron donor, dicyanovinly (DCV) as an electron acceptor and phenyl (ph) ring as the central bridge. The results showed that after photoexcitation into the higher excited S2 state, ultrafast internal conversion into S1 takes place. The rate of S2 → S1 internal conversion is markedly faster (with a typical time of 120 fs ± 20 fs) than the diffusive solvation process. On the other hand, the lifetime of the relaxed S1 state was strongly dependent on the solvent polarity, changing from 40 to 50 ps in acetonitrile to ∼20 ps in cyclohexane. Time-resolved fluorescence data also showed subpicosecond transient component that is attributable to the spectral relaxation caused by solvation and/or vibrational relaxation in the S1 state.",

keywords = "Charge transfer, Time-resolved fluorescence, Ultrafast internal conversion",

author = "Mohammed, {Omar F.} and Sarhan, {Abdelwareth A.O.}",

note = "Funding Information: We thank Professor Tahei Tahara and Dr. Satoshi Takeuchi for their assistance and useful discussions on the time-resolved experiments which have been done at RIKEN. We thank Japan Society for the Promotion of Science (JSPS) for providing a fellowship to Omar F. Mohammed. This work was also supported by chemistry department, Assiut University, Egypt.",

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doi = "10.1016/j.chemphys.2010.04.014",

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AU - Mohammed, Omar F.

AU - Sarhan, Abdelwareth A.O.

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PY - 2010/6/16

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N2 - We employed both femtosecond fluorescence up-conversion and transient absorption techniques with ∼150 fs time resolution to study the excited-state deactivation process of an intra-molecular charge transfer model compound, 4-(ferrocen-1-yl)benzylidene-malononitrile (Fc-ph-DCV), which consists of ferrocene (Fc) unit as an electron donor, dicyanovinly (DCV) as an electron acceptor and phenyl (ph) ring as the central bridge. The results showed that after photoexcitation into the higher excited S2 state, ultrafast internal conversion into S1 takes place. The rate of S2 → S1 internal conversion is markedly faster (with a typical time of 120 fs ± 20 fs) than the diffusive solvation process. On the other hand, the lifetime of the relaxed S1 state was strongly dependent on the solvent polarity, changing from 40 to 50 ps in acetonitrile to ∼20 ps in cyclohexane. Time-resolved fluorescence data also showed subpicosecond transient component that is attributable to the spectral relaxation caused by solvation and/or vibrational relaxation in the S1 state.

AB - We employed both femtosecond fluorescence up-conversion and transient absorption techniques with ∼150 fs time resolution to study the excited-state deactivation process of an intra-molecular charge transfer model compound, 4-(ferrocen-1-yl)benzylidene-malononitrile (Fc-ph-DCV), which consists of ferrocene (Fc) unit as an electron donor, dicyanovinly (DCV) as an electron acceptor and phenyl (ph) ring as the central bridge. The results showed that after photoexcitation into the higher excited S2 state, ultrafast internal conversion into S1 takes place. The rate of S2 → S1 internal conversion is markedly faster (with a typical time of 120 fs ± 20 fs) than the diffusive solvation process. On the other hand, the lifetime of the relaxed S1 state was strongly dependent on the solvent polarity, changing from 40 to 50 ps in acetonitrile to ∼20 ps in cyclohexane. Time-resolved fluorescence data also showed subpicosecond transient component that is attributable to the spectral relaxation caused by solvation and/or vibrational relaxation in the S1 state.

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Ultrafast excited-state dynamics of ferrocene-bridge-acceptor system

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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