scholarly journals Quantum Beats in Transient Spectroscopy of J-Aggregates

1996 ◽  
Vol 16 (3) ◽  
pp. 179-196
Author(s):  
H. Glaeske ◽  
K.-H. Feller ◽  
E. Gaišaukas ◽  
L. Knöll
Keyword(s):  
Transient Absorption ◽  
Temporal Evolution ◽  
Quantum Beat ◽  
Quantum Beats ◽  
Level System ◽  
Temperature Dependent ◽  
Phase Relaxation ◽  
Experimental Conditions ◽  
J Aggregates ◽  
Transient Spectroscopy

Quantum beats in transient absorption of PIC-J-aggregates, modelled by a modified 3-level-system are calculated. Experimental conditions for the possibility of their observation are investigated. The influence of the temperature dependent phase relaxation on the temporal evolution of quantum beat signals is considered.

QUANTUM BEATS IN SEMICONDUCTORS

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1621-1625
Author(s):  
CHRISTIAN H. ZIENER ◽  
THOMAS KAMPF ◽  
WOLFGANG R. BAUER ◽  
PETER M. JAKOB ◽  
STEPHAN GLUTSCH ◽  
...  
Keyword(s):  
Faraday Rotation ◽  
Beat Frequency ◽  
Magnetic Semiconductor ◽  
Quantum Beat ◽  
Quantum Beats ◽  
Level System ◽  
Pump Probe ◽  
Light Pulses ◽  
Band Parameter ◽  
Band Dispersion

In this paper we present a new method to calculate the Faraday rotation using the Jones calculus applicable to light pulses. This result is used to calculate the quantum beats in a magnetic semiconductor generated by pump-probe experiments in Faraday geometry. Considering a six level system and neglecting band dispersion as well as Coulomb interaction we find the Luttinger parameter of the valence band to be the only band parameter contributing to the quantum beat frequency.

scholarly journals Novel Nanohybrids Based on Supramolecular Assemblies of Meso-tetrakis-(4-sulfonatophenyl) Porphyrin J-aggregates and Amine-Functionalized Carbon Nanotubes

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 669 ◽  
Author(s):  
Mariachiara Trapani ◽  
Antonino Mazzaglia ◽  
Anna Piperno ◽  
Annalaura Cordaro ◽  
Roberto Zagami ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Transmission Electron Microscopy ◽  
Fluorescence Emission ◽  
Resonance Light Scattering ◽  
Therapeutic Window ◽  
Multiwalled Carbon ◽  
Experimental Conditions ◽  
Transmission Electron ◽  
J Aggregates

The ability of multiwalled carbon nanotubes (MWCNTs) covalently functionalized with polyamine chains of different length (ethylenediamine, EDA and tetraethylenepentamine, EPA) to induce the J-aggregation of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) was investigated in different experimental conditions. Under mild acidic conditions, protonated amino groups allow for the assembly by electrostatic interaction with the diacid form of TPPS, leading to hybrid nanomaterials. The presence of only one pendant amino group for a chain in EDA does not lead to any aggregation, whereas EPA (with four amine groups for chain) is effective in inducing J-aggregation using different mixing protocols. These nanohybrids have been characterized through UV/Vis extinction, fluorescence emission, resonance light scattering and circular dichroism spectroscopy. Their morphology and chemical composition have been elucidated through transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). TEM and STEM analysis evidence single or bundles of MWCNTs in contact with TPPS J-aggregates nanotubes. The nanohybrids are quite stable for days, even in aqueous solutions mimicking physiological medium (NaCl 0.15 M). This property, together with their peculiar optical features in the therapeutic window of visible spectrum, make them potentially useful for biomedical applications.

Improved SiO2/ 4H-SiC Interface Defect Density Using Forming Gas Annealing

2019 ◽  
Vol 963 ◽  
pp. 465-468
Author(s):  
Stephan Wirths ◽  
Giovanni Alfieri ◽  
Alyssa Prasmusinto ◽  
Andrei Mihaila ◽  
Lukas Kranz ◽  
...  
Keyword(s):  
Defect Density ◽  
Deep Level ◽  
Flat Band ◽  
Temperature Dependent ◽  
Mos Capacitors ◽  
Interface Defect ◽  
Before And After ◽  
Oxide Deposition ◽  
Transient Spectroscopy ◽  
Post Deposition

We investigated the influence of forming gas annealing (FGA) before and after oxide deposition on the SiO2/4H-SiC interface defect density (Dit). For MOS capacitors (MOSCAPs) that were processed using FGAs at temperatures above 1050°C, CV characterization revealed decreased flat band voltage shifts and stretch-out for different sweep directions and frequencies. Moreover, constant-capacitance deep level transient spectroscopy (CC-DLTS) was performed and showed Dit levels below 1012 cm-2eV-1 for post deposition FGA at 1200°C. Finally, lateral MOSFETs were fabricated to analyze the temperature-dependent threshold voltage (Vth) shift.

Macroscopic transient absorption in a V-type three-level system

2020 ◽  
Vol 53 (17) ◽  
pp. 175601 ◽  
Author(s):  
Yu He ◽  
Rao Chen ◽  
Fujun Wang ◽  
Adrian N Pfeiffer ◽  
Yuxuan Zhang ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Level System

Transport Properties and Conduction Band Offset of n-ZnO/n-6H-SiC Heterostructures

2006 ◽  
Vol 957 ◽  
Author(s):  
Yahya Alivov ◽  
Xiao Bo ◽  
Fan Qian ◽  
Daniel Johnstone ◽  
Cole Litton ◽  
...  
Keyword(s):  
Conduction Band ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Band Offset ◽  
Measured Temperature ◽  
Temperature Dependent ◽  
Conduction Band Offset ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Transient Spectroscopy

ABSTRACTThe conduction band offset of n-ZnO/n-6H-SiC heterostructures fabricated by rf-sputtered ZnO on commercial n-type 6H-SiC substrates has been measured. Temperature dependent current-voltage characteristics, photocapacitance, and deep level transient spectroscopy measurements showed the conduction band offsets to be 1.25 eV, 1.1 eV, and 1.22 eV, respectively.

Quantum beats in J-aggregates

1996 ◽  
Author(s):  
H. Glaeske ◽  
Karl-Heinz Feller ◽  
E. Gaizauskas
Keyword(s):  
Quantum Beats ◽  
J Aggregates

scholarly journals Contrasting Electron and Hole Transfer Dynamics from CH(NH2)2PbI3 Perovskite Quantum Dots to Charge Transport Layers

2020 ◽  
Vol 10 (16) ◽  
pp. 5553
Author(s):  
Zhigang Lou ◽  
Shuyan Liang ◽  
Jiabei Yuan ◽  
Kang Ji ◽  
Jianyu Yuan ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Charge Transport ◽  
Transient Absorption ◽  
Diffusion Length ◽  
Temporal Evolution ◽  
Fine Tuning ◽  
Transient Absorption Spectroscopy ◽  
Hole Transfer ◽  
Perovskite Quantum Dots ◽  
Hole Diffusion Length

In this work, the ultrafast transient absorption spectroscopy (TAs) was utilized to first investigate the charge transfer from the emerging FAPbI3 (FA = CH(NH2)2) perovskite quantum dots (PQDs) to charge transport layers. Specifically, we compared the TAs in pure FAPbI3 PQDs, PQDs grown with both electron and hole transfer layers (ETL and HTL), and PQDs with only ETL or HTL. The TA signals induced by photoexcited electrons decay much faster in PQDs samples with the ETL (~20 ps) compared to the pure FAPbI3 PQDs (>1 ns). These results reveal that electrons can effectively transport between coupled PQDs and transfer to the ETL (TiO2) at a time scale of 20 ps, much faster than the bimolecular charge recombination inside the PQDs (>1 ns), and the electron transfer efficiency is estimated to be close to 100%. In contrast, the temporal evolution of the TA signals in the PQDs with and without HTL exhibit negligible change, and no substantive hole transfer to the HTL (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], PTAA) occurs within 1 ns. The much slower hole transfer implies the further potential of increasing the overall photo-carrier conversion efficiency through enhancing the hole diffusion length and fine-tuning the coupling between the HTL and PQDs.

Excited state hyperfine structures in 133Cs using quantum beat spectroscopy

1991 ◽  
Vol 69 (7) ◽  
pp. 808-812 ◽  
Author(s):  
J. Sagle ◽  
W. A. van Wijngaarden
Keyword(s):  
Excited State ◽  
Hyperfine Interaction ◽  
Quadrupole Moment ◽  
Magnetic Dipole ◽  
Electric Quadrupole ◽  
Quantum Beat ◽  
Quantum Beats ◽  
Electric Quadrupole Moment ◽  
Coupling Constant ◽  
Hyperfine Structures

Quantum beats arising from the hyperfine interaction were observed in the fluorescence produced when the 8D3/2, 9D3/2, and 10D3/2 states of 133Cs radiatively decayed to the 6P1/2 state. The period of the beats equals the reciprocal of the magnetic dipole coupling constant a since the 133Cs nucleus has a negligibly small electric quadrupole moment. The results are a = 3.95 ± 0.01, 2.38 ± 0.01, and 1.54 ± 0.02 MHz for the 8D3/2, 9D3/2, and 10D3/2 states, respectively.

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