Ultrafast dynamics of the indoline dye D149 on electrodeposited ZnO and sintered ZrO2 and TiO2 thin films

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dc.identifier.uri http://dx.doi.org/10.15488/2215
dc.identifier.uri http://www.repo.uni-hannover.de/handle/123456789/2240
dc.contributor.author Oum, Kawon
dc.contributor.author Lohse, Peter W.
dc.contributor.author Flender, Oliver
dc.contributor.author Klein, Johannes R.
dc.contributor.author Scholz, Mirko
dc.contributor.author Lenzer, Thomas
dc.contributor.author Du, Juan
dc.contributor.author Oekermann, Torsten
dc.date.accessioned 2017-11-01T13:25:07Z
dc.date.available 2017-11-01T13:25:07Z
dc.date.issued 2012
dc.identifier.citation Oum, K.; Lohse, P.W.; Flender, O.; Klein, J.R.; Scholz, M. et al.: Ultrafast dynamics of the indoline dye D149 on electrodeposited ZnO and sintered ZrO2 and TiO2 thin films. In: Physical Chemistry Chemical Physics 14 (2012), Nr. 44, S. 15429-15437. DOI: https://doi.org/10.1039/c2cp42961f
dc.description.abstract The ultrafast photoinjection and subsequent relaxation steps of the indoline dye D149 were investigated in detail for a mesoporous electrodeposited ZnO thin film and compared with experiments on sintered TiO2 and ZrO2 thin films, all in contact with air, using pump-supercontinuum probe (PSCP) transient absorption spectroscopy in the range 370-770 nm. D149 efficiently injects electrons into the ZnO surface with time constants from ≤70 fs (time-resolution-limited) up to 250 fs, without the presence of slower components. Subsequent spectral dynamics with a time constant of 20 ps and no accompanying change in the oscillator strength are assigned to a transient Stark shift of the electronic absorption spectrum of D149 molecules in the electronic ground state due to the local electric field exerted by the D149 •+ radical cations and conduction band electrons in ZnO. This interpretation is consistent with the shape of the relaxed PSCP spectrum at long times, which resembles the first derivative of the inverted steady-state absorption spectrum of D149. In addition, steady-state difference absorption spectra of D149•+ in solution from spectroelectrochemistry display a bleach band with distinctly different position, because no first-order Stark effect is present in that case. Interference features in the PSCP spectra probably arise from a change of the refractive index of ZnO caused by the injected electrons. The 20 ps component in the PSCP spectra is likely a manifestation of the transition from an initially formed bound D149 •+-electron complex to isolated D149•+ and mobile electrons in the ZnO conduction band (which changes the external electric field experienced by D149) and possibly also reorientational motion of D149 molecules in response to the electric field. We identify additional spectral dynamics on a similar timescale, arising from vibrational relaxation of D149•+ by interactions with ZnO. TiO2 exhibits similar dynamics to ZnO. In the case of ZrO2, electron injection accesses trap states, which exhibit a substantial probability for charge recombination. No Stark shift is observed in this case. In addition, the spectroelectrochemical experiments for D149•+ in dichloromethane and acetonitrile, which cover the spectral range up to 2000 nm, provide for the first time access to its complete D0 → D1 absorption band, with the peak located at 1250 and 1055 nm, respectively. Good agreement is obtained with results from DFT/TDDFT calculations of the D149 •+ spectrum employing the MPW1K functional. © 2012 the Owner Societies. eng
dc.language.iso eng
dc.publisher Cambridge : Royal Society of Chemistry
dc.relation.ispartofseries Physical Chemistry Chemical Physics 14 (2012), Nr. 44
dc.rights Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
dc.subject coloring agent eng
dc.subject free radical eng
dc.subject indole derivative eng
dc.subject titanium eng
dc.subject titanium dioxide eng
dc.subject zinc oxide eng
dc.subject zirconium eng
dc.subject zirconium oxide eng
dc.subject article eng
dc.subject chemical structure eng
dc.subject chemistry eng
dc.subject electrochemical analysis eng
dc.subject quantum theory eng
dc.subject Coloring Agents eng
dc.subject Electrochemical Techniques eng
dc.subject Free Radicals eng
dc.subject Indoles eng
dc.subject Molecular Structure eng
dc.subject Quantum Theory eng
dc.subject Titanium eng
dc.subject Zinc Oxide eng
dc.subject Zirconium eng
dc.subject.ddc 540 | Chemie ger
dc.title Ultrafast dynamics of the indoline dye D149 on electrodeposited ZnO and sintered ZrO2 and TiO2 thin films
dc.type article
dc.type Text
dc.relation.issn 1463-9076
dc.relation.doi https://doi.org/10.1039/c2cp42961f
dc.bibliographicCitation.issue 44
dc.bibliographicCitation.volume 14
dc.bibliographicCitation.firstPage 15429
dc.bibliographicCitation.lastPage 15437
dc.description.version publishedVersion
tib.accessRights frei zug�nglich

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