Details
| Original language | English |
|---|---|
| Pages (from-to) | 9139-9149 |
| Number of pages | 11 |
| Journal | Journal of Physical Chemistry B |
| Volume | 105 |
| Issue number | 38 |
| Publication status | Published - 31 Aug 2001 |
Abstract
Time-resolved fluorescence spectroscopy is used to investigate relaxation of electronic excitations in films of π-conjugated polymer 1 in the ps time domain. The position of the fluorescence band and its width are measured as a function of time and excitation energy. Both low (15 K) and room-temperature behavior are investigated. For high energy excitation, the fluorescence band shows a continuous red shift with time. The energy associated with the maximum of the fluorescence band E is proportional to log(t), with t being the time after excitation. For excitation in the tail of the lowest absorption band, the fluorescence remains stationary and selective excitation of a subset of chromophoric chain segments is possible. At intermediate excitation energy the time required for the excitations to make their first jump depends on the excitation energy and is longer at lower energy. At low temperature and high energy excitation the fluorescence bands are found to narrow with time, while for low energy excitation a broadening with time is observed. The experimental data are consistent with dispersive relaxation dynamics for the photoexcitations by incoherent hopping between localized states. Monte Carlo simulations are performed to obtain the average energy and the width of the energy distribution for an ensemble of photoexcitations in an energetically disordered molecular solid assuming Förster type energy transfer. A Förster radius R0 ∼ 30 Å is found to give good agreement between experiment and simulations. In addition, the measurements indicate that for excitation energies >2.94 eV additional relaxation processes, ascribed to ultrafast intrachain vibrational relaxation, are operative.
ASJC Scopus subject areas
- Chemistry(all)
- Physical and Theoretical Chemistry
- Materials Science(all)
- Surfaces, Coatings and Films
- Materials Science(all)
- Materials Chemistry
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In: Journal of Physical Chemistry B, Vol. 105, No. 38, 31.08.2001, p. 9139-9149.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Dispersive relaxation dynamics of photoexcitations in a polyfluorene film involving energy transfer
T2 - Experiment and Monte Carlo simulations
AU - Meskers, Stefan C.J.
AU - Hübner, Jens
AU - Oestreich, Michael
AU - Bässler, Heinz
PY - 2001/8/31
Y1 - 2001/8/31
N2 - Time-resolved fluorescence spectroscopy is used to investigate relaxation of electronic excitations in films of π-conjugated polymer 1 in the ps time domain. The position of the fluorescence band and its width are measured as a function of time and excitation energy. Both low (15 K) and room-temperature behavior are investigated. For high energy excitation, the fluorescence band shows a continuous red shift with time. The energy associated with the maximum of the fluorescence band E is proportional to log(t), with t being the time after excitation. For excitation in the tail of the lowest absorption band, the fluorescence remains stationary and selective excitation of a subset of chromophoric chain segments is possible. At intermediate excitation energy the time required for the excitations to make their first jump depends on the excitation energy and is longer at lower energy. At low temperature and high energy excitation the fluorescence bands are found to narrow with time, while for low energy excitation a broadening with time is observed. The experimental data are consistent with dispersive relaxation dynamics for the photoexcitations by incoherent hopping between localized states. Monte Carlo simulations are performed to obtain the average energy and the width of the energy distribution for an ensemble of photoexcitations in an energetically disordered molecular solid assuming Förster type energy transfer. A Förster radius R0 ∼ 30 Å is found to give good agreement between experiment and simulations. In addition, the measurements indicate that for excitation energies >2.94 eV additional relaxation processes, ascribed to ultrafast intrachain vibrational relaxation, are operative.
AB - Time-resolved fluorescence spectroscopy is used to investigate relaxation of electronic excitations in films of π-conjugated polymer 1 in the ps time domain. The position of the fluorescence band and its width are measured as a function of time and excitation energy. Both low (15 K) and room-temperature behavior are investigated. For high energy excitation, the fluorescence band shows a continuous red shift with time. The energy associated with the maximum of the fluorescence band E is proportional to log(t), with t being the time after excitation. For excitation in the tail of the lowest absorption band, the fluorescence remains stationary and selective excitation of a subset of chromophoric chain segments is possible. At intermediate excitation energy the time required for the excitations to make their first jump depends on the excitation energy and is longer at lower energy. At low temperature and high energy excitation the fluorescence bands are found to narrow with time, while for low energy excitation a broadening with time is observed. The experimental data are consistent with dispersive relaxation dynamics for the photoexcitations by incoherent hopping between localized states. Monte Carlo simulations are performed to obtain the average energy and the width of the energy distribution for an ensemble of photoexcitations in an energetically disordered molecular solid assuming Förster type energy transfer. A Förster radius R0 ∼ 30 Å is found to give good agreement between experiment and simulations. In addition, the measurements indicate that for excitation energies >2.94 eV additional relaxation processes, ascribed to ultrafast intrachain vibrational relaxation, are operative.
UR - http://www.scopus.com/inward/record.url?scp=0035960175&partnerID=8YFLogxK
U2 - 10.1021/jp0113331
DO - 10.1021/jp0113331
M3 - Article
AN - SCOPUS:0035960175
VL - 105
SP - 9139
EP - 9149
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1089-5647
IS - 38
ER -