Influence of Electron-withdrawing Substituents on Photoelectrochemical Surface Phenomena at Phthalocyanine Thin Film Electrodes

1999 ◽  
Vol 03 (06) ◽  
pp. 444-452 ◽  
Author(s):  
TORSTEN OEKERMANN ◽  
DERCK SCHLETTWEIN ◽  
NILS I. JAEGER ◽  
DIETER WÖHRLE
Keyword(s):  
Charge Transfer ◽  
Steady State ◽  
Electrolyte Concentration ◽  
Surface States ◽  
Surface Phenomena ◽  
Time Resolved ◽  
Photogenerated Electrons ◽  
Millisecond Range ◽  
Electron Withdrawing Substituents

The influence of electron-withdrawing substituents on the photoelectrochemical properties of phthalocyanines is shown in a comparison between hexadecafluorophthalocyaninatozinc(II) ( F 16 PcZn ) and the unsubstituted phthalocyaninatozinc(II) ( PcZn ). The role of surface states in the photoelectrochemistry of both materials has been investigated by time-resolved photocurrent measurements in the millisecond range. The charging and discharging of surface states could clearly be seen as spikes at the beginning and the end of illumination. Surface states were filled with photogenerated electrons at PcZn and with photogenerated holes at F 16 PcZn . In the steady state under illumination only cathodic photocurrents were detected at PcZn , while at F 16 PcZn both cathodic and anodic photocurrents were observed. An adsorption step of electroactive species prior to the charge transfer was derived from the dependence of the steady state photocurrents on the electrolyte concentration for both materials. The concentration dependence of the charging and discharging currents, however, showed that charge transfer from surface states to the electrolyte occurs at PcZn , while at F 16 PcZn the surface states only represent recombination centres.

Role of Tryptophan in Protein–Nanocrystals Interaction: Energy or Charge Transfer

2018 ◽  
Vol 233 (1) ◽  
pp. 41-54 ◽  
Author(s):  
Mona Mittal ◽  
Saurabh Gautam ◽  
Pramit Kumar Chowdhury ◽  
Shashank Deep ◽  
Sameer Sapra
Keyword(s):  
Charge Transfer ◽  
Steady State ◽  
Semiconductor Nanocrystals ◽  
Binding Model ◽  
Time Resolved ◽  
Tryptophan Residues ◽  
Mechanism Of Interaction ◽  
Pl Intensity ◽  
Time Resolved Photoluminescence

Abstract The understanding of the interaction between the semiconductor nanocrystals (NCs) and the proteins are essential for design and fabrication of nanocomposites for application in the field of biotechnology. Herein, we have studied the interaction between CdTe NCs and the proteins by steady-state and time-resolved photoluminescence (PL) spectroscopy. The steady-state PL intensity of CdTe NCs is quenched and enhanced in the presence of lysozyme and bovine serum albumin, respectively. However, the PL intensity of CdTe NCs is not affected with α-synuclein, indicating the role of tryptophan moiety in the protein–NCs interaction. The detailed analysis of PL data allows us to elucidate the dominant mechanism of interaction, i.e. charge or energy transfer, depending on the location of tryptophan residues in the protein. Assuming a Poisson statistic of lysozymes around NCs, the Poisson binding model is used to understand the kinetics of charge transfer from CdTe NCs to the lysozyme. It provides the average number of lysozymes present on the surface of one CdTe NC.

Photochemistry of triphenylamine (TPA) in homogeneous solution and the role of transient N-phenyl-4a,4b-dihydrocarbazole. A steady-state and time-resolved investigation.

2021 ◽  
Author(s):  
Stefano Protti ◽  
Mariella Mella ◽  
Sergio Mauricio Bonesi
Keyword(s):  
Steady State ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Homogeneous Solution ◽  
Laser Flash ◽  
Time Resolved ◽  
Homogeneous Media

Abstract. The photoreactivity of triphenylamine in homogeneous media has been investigated by means of laser flash photolysis spectroscopy and preparative experiments. The goal of this study consists in the evaluation...

Photoinduced energy and charge transfer in a bis(triphenylamine)–BODIPY–C60 artificial photosynthetic system

RSC Advances ◽  
2016 ◽  
Vol 6 (62) ◽  
pp. 57293-57305 ◽  
Author(s):  
Jian-Yong Liu ◽  
Xue-Ni Hou ◽  
Ye Tian ◽  
Lizhi Jiang ◽  
Shuiquan Deng ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Steady State ◽  
Spectroscopic Techniques ◽  
Time Resolved ◽  
Photosynthetic System ◽  
Transfer Processes ◽  
Nonpolar Solvents ◽  
System P ◽  
Artificial Photosynthetic

The bis(triphenylamine)–BODIPY–C60 artificial photosynthetic system has been prepared and studied for its photoinduced transfer processes in polar and nonpolar solvents using various steady-state and time-resolved spectroscopic techniques.

scholarly journals Spatiotemporal imaging of anisotropic charge transfer in photocatalyst particles

2021 ◽  
Author(s):  
Can Li ◽  
Ruotian Chen ◽  
Zefeng Ren ◽  
Yu Liang ◽  
Thomas Dittrich ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Rational Design ◽  
Catalytic Surface ◽  
Time Resolved ◽  
Transfer Processes ◽  
Ballistic Electron ◽  
Photogenerated Electrons ◽  
Particle Level ◽  
Efficient Charge ◽  
Charge Transfer Dynamics

Abstract Water-splitting reactions using photocatalyst particles are promising routes for solar fuel production1-4. Photoinduced charge transfer from a photocatalyst to catalytic surface sites is key in ensuring photocatalytic efficiency5; however, it is challenging to understand this process, which spans a wide spatiotemporal range from nanometers to micrometers and from femtoseconds to seconds6-8. Although the steady-state charge distribution on single photocatalyst particles has been mapped using microscopic techniques9-11 and the averaged charge transfer dynamics in photocatalyst aggregations have been revealed via time-resolved spectroscopy12,13, spatiotemporally evolving charge transfer processes in single photocatalyst particles cannot be tracked, and the mechanism of charge transfer is unknown. Here, we report spatiotemporally resolved surface photovoltage measurements on Cu2O photocatalyst particles to map complete charge transfer processes throughout the femtosecond to second time scale at the single-particle level. We found that photogenerated electrons are transferred to the catalytic surface ballistically on a sub-picosecond timescale and are retained at this location for the duration, whereas photogenerated holes are transferred to a spatially separated surface and stabilized via selective trapping on a microsecond timescale. We demonstrate that these ballistic electron transfer and anisotropic trapping regimes, which challenge the classical perception of the drift–diffusion model, contribute to efficient charge separation in photocatalysis and improve the photocatalytic performance. We anticipate our findings to demonstrate the universality of other photoelectronic devices and facilitate the rational design of photocatalysts.

Dramatic luminescence signal from a Co(ii)-based metal–organic compound due to the construction of charge-transfer bands with Al3+ and Fe3+ ions in water: steady-state and time-resolved spectroscopic studies

2020 ◽  
Vol 44 (11) ◽  
pp. 4376-4385 ◽  
Author(s):  
Pooja Daga ◽  
Prakash Majee ◽  
Debal Kanti Singha ◽  
Priyanka Manna ◽  
Sayani Hui ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Steady State ◽  
Organic Compound ◽  
Spectroscopic Studies ◽  
Charge Transfer Complexes ◽  
Time Resolved ◽  
Luminescence Signal ◽  
Turn On ◽  
Metal Organic

A Co(ii)-based metal–organic compound exhibits luminescence turn-on by Al3+ and quenching by Fe3+ due to the formation of charge-transfer complexes/adducts.

Symmetry-breaking charge transfer in the excited state of directly linked push–pull porphyrin arrays

2017 ◽  
Vol 19 (21) ◽  
pp. 13970-13977 ◽  
Author(s):  
Taeyeon Kim ◽  
Jinseok Kim ◽  
Hirotaka Mori ◽  
Seongchul Park ◽  
Manho Lim ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Steady State ◽  
Symmetry Breaking ◽  
Time Resolved ◽  
Spectroscopic Measurements

We revealed a symmetry-breaking charge transfer (SBCT) process in the excited state of a directly linked push–pull porphyrin dyad (AD) and triad (ADA) via both steady-state and time-resolved spectroscopic measurements.

Many-electron theory of resonant charge transfer: Role of surface states in He andHe+scattering off Si(100)

1992 ◽  
Vol 45 (23) ◽  
pp. 13407-13416 ◽  
Author(s):  
B. L. Burrows ◽  
A. T. Amos ◽  
S. G. Davison ◽  
K. W. Sulston
Keyword(s):  
Charge Transfer ◽  
Surface States ◽  
Electron Theory ◽  
Resonant Charge Transfer

scholarly journals Ultrafast evolution of bulk, surface and surface resonance states in photoexcited $$\hbox {Bi}_{2}\hbox {Te}_{3}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hamoon Hedayat ◽  
Davide Bugini ◽  
Hemian Yi ◽  
Chaoyu Chen ◽  
Xingjiang Zhou ◽  
...  
Keyword(s):  
Surface States ◽  
Photoemission Spectroscopy ◽  
Time Resolved ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Interband Scattering ◽  
Surface Resonance ◽  
Bulk Surface ◽  
Unpolarized Electron ◽  
Topological Surface

AbstractWe use circular dichroism (CD) in time- and angle-resolved photoemission spectroscopy (trARPES) to measure the femtosecond charge dynamics in the topological insulator (TI) $$\hbox {Bi}_{2}\hbox {Te}_{3}$$ Bi 2 Te 3 . We detect clear CD signatures from topological surface states (TSS) and surface resonance (SR) states. In time-resolved measurements, independently from the pump polarization or intensity, the CD shows a dynamics which provides access to the unexplored electronic evolution in unoccupied states of $$\hbox {Bi}_{2}\hbox {Te}_{3}$$ Bi 2 Te 3 . In particular, we are able to disentangle the unpolarized electron dynamics in the bulk states from the spin-textured TSS and SR states on the femtosecond timescale. Our study demonstrates that photoexcitation mainly involves the bulk states and is followed by sub-picosecond transport to the surface. This provides essential details on intra- and interband scattering in the relaxation process of TSS and SR states. Our results reveal the significant role of SRs in the subtle ultrafast interaction between bulk and surface states of TIs.

Sign in / Sign up

Export Citation Format

Share Document