Femtosecond pump-supercontinuum probe and transient lens spectroscopy of adonixanthin

Lenzer, Thomas; Schubert, Steffen; Ehlers, Florian; Lohse, Peter W.; Scholz, Mirko; Oum, Kawon

doi:10.1016/j.abb.2008.11.026

Cited by 38 publications

(37 citation statements)

References 25 publications

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“…Ultrafast broadband transient absorption experiments were carried out using our setup for pump-supercontinuum probe (PSCP) spectroscopy [7,[27][28][29][30]. The carotenoid sample was excited by a NOPA ( pump ca.…”

Section: Pump-supercontinuum Probe (Pscp) Spectroscopymentioning

confidence: 99%

Excited State Dynamics of Selected All-trans C₄₀ Xanthophyll Carotenoids

Ehlers¹,

Scholz²,

Lenzer³

et al. 2015

Zeitschrift Für Physikalische Chemie

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We investigated the excited state dynamics of selected all-trans C 40 xanthophyll carotenoids by ultrafast pump-supercontinuum probe (PSCP) spectroscopy in the spectral range 350-770 nm upon photoexcitation by a femtosecond laser (ca. 80 fs pulse length) near 500 nm in acetone. The following carotenoids were selected considering a systematic variation of the number and position of carbonyl (CO) and hydroxyl (OH) functional groups on the -ionone rings and the change of the effective conjugation length of the polyene system: -cryptoxanthin (1), echinenone (2), 3-hydroxyechinenone (3), 3 -hydroxyechinenone (4), canthaxanthin (5), adonirubin (6) and astaxanthin (7).The carotenoids featuring an increasing conjugation length, for example, (1), (3) and (6), showed a systematically shorter S 1 lifetime of 8.7, 6.2 and 4.7 ps, respectively. Carotenoids with OH groups adjacent to a CO group showed slightly broader steady-state and transient absorption bands, but the influence on the S 1 lifetime was minor compared to the case of CO substitution. Moreover, in all cases we observed clearly visible "S * signals", namely a longer-lived characteristic S 0 → S 2 red-edge absorption and a negative signal in the S 0 → S 2 bleach region. This spectral signature is assigned to highly vibrationally excited molecules in the ground electronic state S * 0 which are generated by internal conversion from S 1 . The S * 0 species cool with a time constant of 9.2-9.6 ps in the case of the ketosubstituted carotenoids (2)-(7), whereas we obtain a larger value of 13.2 ps for (1) which does not have a keto group. Our findings are supported by results from a global kinetic analysis procedure.

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Section: Pump-supercontinuum Probe (Pscp) Spectroscopymentioning

confidence: 99%

Excited State Dynamics of Selected All-trans C₄₀ Xanthophyll Carotenoids

Ehlers¹,

Scholz²,

Lenzer³

et al. 2015

Zeitschrift Für Physikalische Chemie

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“…23,[25][26][27] For the experiments in acetonitrile, a flow cell (1 mm path length) with a 200 mm thick quartz entrance window was used. Thin films were mounted on an x/y translation stage and moved in a plane perpendicular to the probe light path to expose a fresh spot for every laser shot.…”

Section: Pump-supercontinuum Probe (Pscp) Spectroscopymentioning

confidence: 99%

Photoinduced ultrafast dynamics of the triphenylamine-based organic sensitizer D35 on TiO2, ZrO2 and in acetonitrile

Oum

Lohse

Klein

et al. 2013

Phys. Chem. Chem. Phys.

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The relaxation dynamics of the dye D35 has been characterized by transient absorption spectroscopy in acetonitrile and on TiO 2 and ZrO 2 thin films. In acetonitrile, upon photoexcitation of the dye via the S 0 -S 1 transition, we observed ultrafast solvation dynamics with subpicosecond time constants.Subsequent decay of the S 1 excited state absorption (ESA) band with a 7.1 ps time constant is tentatively assigned to structural relaxation in the excited state, and a spectral decay with 203 ps time constant results from internal conversion (IC) back to S 0 . On TiO 2 , we observed fast (o90 fs) electron injection from the S 1 state of D35 into the TiO 2 conduction band, followed by a biphasic dynamics arising from changes in a transient Stark field at the interface, with time constants of 0.8 and 12 ps, resulting in a characteristic blue-shift of the S 0 -S 1 absorption band. Several processes can contribute to this spectral shift: (i) photoexcitation induces immediate formation of D35 + radical cations, which initially form electron-cation complexes; (ii) dissociation of these complexes generates mobile electrons, and when they start diffusing in the mesoporous TiO 2 , the local electrostatic field may change; (iii) this may trigger the reorientation of D35 molecules in the changing electric field. A slower spectral decay on a nanosecond timescale is interpreted as a reduction of the local Stark field, as mobile electrons move deeper into TiO 2 and are progressively screened. Multiexponential electron-cation recombination occurs on much longer timescales, with time constants of 30 ms, 170 ms and 1.4 ms. For D35 adsorbed on ZrO 2 , there is no clear evidence for a transient Stark shift, which suggests that initially formed cation-electron (trap state) complexes do not dissociate to form mobile conduction band electrons.Multiexponential decay with time constants of 4, 35, and 550 ps is assigned to recombination between cations and trapped electrons, and also to a fraction of D35 molecules in S 1 which decay by IC to S 0 .Differential steady-state absorption spectra of D35 + in acetonitrile and dichloromethane provide access to the complete D 0 -D 1 band. The absorption spectra of D35 and D35 + are well described by TDDFT calculations employing the MPW1K functional.

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“…[34][35][36] An overview of the principle of PSCP spectroscopy can be found elsewhere. 37 The sample was excited using a NOPA with a center wavelength of 510 or 630 nm and probed by a supercontinuum (370-770 nm) generated in a 1 mm thick CaF 2 plate.…”

Section: Pump-supercontinuum Probe (Pscp) Spectroscopymentioning

confidence: 99%

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

Oum

Lohse

Flender

et al. 2012

Phys. Chem. Chem. Phys.

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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 TiO 2 and ZrO 2 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 r70 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. TiO 2 exhibits similar dynamics to ZnO. In the case of ZrO 2 , 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 D 0 -D 1 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.

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Femtosecond pump-supercontinuum probe and transient lens spectroscopy of adonixanthin

Cited by 38 publications

References 25 publications

Excited State Dynamics of Selected All-trans C₄₀ Xanthophyll Carotenoids

Excited State Dynamics of Selected All-trans C₄₀ Xanthophyll Carotenoids

Photoinduced ultrafast dynamics of the triphenylamine-based organic sensitizer D35 on TiO2, ZrO2 and in acetonitrile

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

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Femtosecond pump-supercontinuum probe and transient lens spectroscopy of adonixanthin

Cited by 38 publications

References 25 publications

Excited State Dynamics of Selected All-trans C40 Xanthophyll Carotenoids

Excited State Dynamics of Selected All-trans C40 Xanthophyll Carotenoids

Photoinduced ultrafast dynamics of the triphenylamine-based organic sensitizer D35 on TiO2, ZrO2 and in acetonitrile

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

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Excited State Dynamics of Selected All-trans C₄₀ Xanthophyll Carotenoids

Excited State Dynamics of Selected All-trans C₄₀ Xanthophyll Carotenoids