A work station for laboratory data acquisition: flourescence lifetime apparatus

Federici, John F.; Helman, W. P.; Hug, Gordon L.; Kane, Carolyn L.; Patterson, L. K.

doi:10.1016/0097-8485(85)80002-4

Cited by 11 publications

(5 citation statements)

References 6 publications

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“…Emission lifetime measurements were carried out using the electrochemical cell as explained above. The experiments were performed by a time-correlated single-photon counting technique using an apparatus that has been described elsewhere . The excitation source was a mode-locked, Q-switched Quantronix 416 Nd:YAG laser which provided 80 ps pulses of 355 nm light with a frequency of 5 kHz and an integrated power of 10 mW.…”

Section: Methodsmentioning

confidence: 99%

Photosensitization of Nanocrystalline Semiconductor Films. Modulation of Electron Transfer between Excited Ruthenium Complex and SnO₂ Nanocrystallites with an Externally Applied Bias

et al. 1996

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In situ spectroelectrochemical measurements have been carried out to probe the charge injection from excited Ru(bpy) 2 (dcbpy) 2+ , Ru(II), into the SnO 2 nanocrystallites. The dependence of luminescence yield and lifetime at various applied potentials suggests that the heterogeneous electron transfer from excited sensitizer into the semiconductor can be controlled by the externally applied electrochemical bias. The maximum quenching is seen at positive potentials while an increase in the luminescence yield and lifetime is seen at negative potentials. Laser flash photolysis of Ru(II)-modified SnO 2 nanocrystalline film has been carried out to record the transient absorption spectra at different applied potentials. The yield of electron transfer product, Ru(III), decreases as the applied bias is switched to negative potentials. At an applied bias of -0.7 V the only observable transient is the excited Ru(II) complex (Ru(II)*). The maximum apparent electron transfer rate constant, k et (∼4 × 10 8 s -1 ), observed at positive bias agrees with the previously determined electron transfer rate constants from emission lifetime and microwave conductivity experiments. The apparent rate constant for heterogeneous electron transfer is dependent on the applied bias, and it decreases as the difference between the pseudo-Fermi level of SnO 2 and oxidation potential of Ru(II)* decreases. These results suggest that the decreased rate of charge injection is responsible for lower IPCE (incident photon-to-photocurrent efficiency) observed in photoelectrochemical cells under negative bias. No significant change in the rate of reverse electron transfer was observed at potentials greater than -0.4 V.

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Section: Methodsmentioning

confidence: 99%

Photosensitization of Nanocrystalline Semiconductor Films. Modulation of Electron Transfer between Excited Ruthenium Complex and SnO₂ Nanocrystallites with an Externally Applied Bias

et al. 1996

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“…Lifetime Measurements. Emission lifetime measurements were performed by time-correlated single-photon counting using an apparatus that has been described elsewhere . The excitation source was a mode-locked, Q-switched Quantronix 416 Nd:YAG laser which provided 80 ps pulses of 355 nm light with a frequency of 5 kHz and an integrated power of 10 mW.…”

Section: Methodsmentioning

confidence: 99%

Photoelectrochemistry of Composite Semiconductor Thin Films. Photosensitization of SnO₂/CdS Coupled Nanocrystallites with a Ruthenium Polypyridyl Complex

and¹,

Hotchandani²,

and³

et al. 1997

J. Phys. Chem. B

161

111

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The charge injection from an excited Ru(II) complex (viz., (Ru(bpy)2(L))2+, where L = 4-(2,2‘-bipyrid-4-yl)phenyl diphosphonate) into SnO2 and SnO2/CdS films is investigated to elucidate the beneficial effect of composite semiconductor systems. The electrons injected from excited Ru(II) into CdS are transferred quickly into SnO2 nanoclusters, thus promoting the charge separation. Photoelectrochemical measurements suggest improved photon to photocurrent charge carrier generation efficiency in the SnO2/CdS composite system. The formation of the oxidation product, Ru(III), and the recovery of the sensitizer are investigated using transient absorption spectroscopy. The rate constant for the back electron transfer in the SnO2/CdS/Ru(II) composite system is slower by a factor of 2−3 than the one observed in the SnO2/Ru(II) system. The beneficial aspects of composite semiconductor systems in photochemical solar cells are presented.

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“…Luminescence measurements were made by exciting Ru(bpy) 2(dcbpy) 2+ adsorbed on ZnO nanocrystalline film with 532 nm pulses of light from a Quanta-Ray DCR1 YAG laser system. 39 The laser output was suitably attenuated to less than ∼2 mJ/pulse and defocused to minimize multiphoton processes. Microwave absorption measurements were made using an apparatus described previously 40 with modifications to improve time response.…”

Section: Methodsmentioning

confidence: 99%

“…Time-Resolved Fluorescence and Microwave Absorption Measurements. Luminescence measurements were made by exciting Ru(bpy) 2 (dcbpy) 2+ adsorbed on ZnO nanocrystalline film with 532 nm pulses of light from a Quanta-Ray DCR1 YAG laser system . The laser output was suitably attenuated to less than ∼2 mJ/pulse and defocused to minimize multiphoton processes.…”

Section: Methodsmentioning

confidence: 99%

Photosensitization of Nanocrystalline ZnO Films by Bis(2,2‘-bipyridine)(2,2‘-bipyridine-4,4‘-dicarboxylic acid)ruthenium(II)

et al. 1997

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Spectral sensitization of nanocrystalline ZnO films has been carried out with ruthenium complex, bis-(2,2′-bipyridine)(2,2′-bipyridine-4,4′-dicarboxylic acid) ruthenium(II) or (Ru(II)). An incident photon to current conversion efficiency (IPCE) of 14% has been obtained for unbiased ZnO/Ru(II) photoelectrochemical cells. This low IPCE has been attributed to the poor light harvesting efficiency (LHE) and charge collection (η c) efficiency. The weak interaction between Ru(II) and ZnO surface which results in poor uptake of Ru(II) on ZnO is responsible for a lower LHE while various charge recombination processes are the cause of poor ηc. To better understand the process of photosensitization of ZnO by Ru(II), the dependence of IPCE and fluorescence on applied bias, and other photoelectrochemical measurements have also been carried out.

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A work station for laboratory data acquisition: flourescence lifetime apparatus

Cited by 11 publications

References 6 publications

Photosensitization of Nanocrystalline Semiconductor Films. Modulation of Electron Transfer between Excited Ruthenium Complex and SnO₂ Nanocrystallites with an Externally Applied Bias

Photosensitization of Nanocrystalline Semiconductor Films. Modulation of Electron Transfer between Excited Ruthenium Complex and SnO₂ Nanocrystallites with an Externally Applied Bias

Photoelectrochemistry of Composite Semiconductor Thin Films. Photosensitization of SnO₂/CdS Coupled Nanocrystallites with a Ruthenium Polypyridyl Complex

Photosensitization of Nanocrystalline ZnO Films by Bis(2,2‘-bipyridine)(2,2‘-bipyridine-4,4‘-dicarboxylic acid)ruthenium(II)

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A work station for laboratory data acquisition: flourescence lifetime apparatus

Cited by 11 publications

References 6 publications

Photosensitization of Nanocrystalline Semiconductor Films. Modulation of Electron Transfer between Excited Ruthenium Complex and SnO2 Nanocrystallites with an Externally Applied Bias

Photosensitization of Nanocrystalline Semiconductor Films. Modulation of Electron Transfer between Excited Ruthenium Complex and SnO2 Nanocrystallites with an Externally Applied Bias

Photoelectrochemistry of Composite Semiconductor Thin Films. Photosensitization of SnO2/CdS Coupled Nanocrystallites with a Ruthenium Polypyridyl Complex

Photosensitization of Nanocrystalline ZnO Films by Bis(2,2‘-bipyridine)(2,2‘-bipyridine-4,4‘-dicarboxylic acid)ruthenium(II)

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Photosensitization of Nanocrystalline Semiconductor Films. Modulation of Electron Transfer between Excited Ruthenium Complex and SnO₂ Nanocrystallites with an Externally Applied Bias

Photosensitization of Nanocrystalline Semiconductor Films. Modulation of Electron Transfer between Excited Ruthenium Complex and SnO₂ Nanocrystallites with an Externally Applied Bias

Photoelectrochemistry of Composite Semiconductor Thin Films. Photosensitization of SnO₂/CdS Coupled Nanocrystallites with a Ruthenium Polypyridyl Complex