Theoretical and Experimental Investigations on the Aggregation‐Enhanced Emission from Dark State: Vibronic Coupling Effect

2020 ◽  
Vol 6 (7) ◽  
pp. 2000255
Author(s):  
Ping‐An Yin ◽  
Qing Wan ◽  
Yingli Niu ◽  
Qian Peng ◽  
Zhiming Wang ◽  
...  
Keyword(s):  
Coupling Effect ◽  
Vibronic Coupling ◽  
Experimental Investigations ◽  
Dark State

scholarly journals Numerical and Experimental Investigations of Coupling Effects in Anisotropic Elastic Rotors

1999 ◽  
Vol 5 (4) ◽  
pp. 263-271 ◽  
Author(s):  
Horst Irretier ◽  
Georges Jacquet-Richardet ◽  
Frank Reuter
Keyword(s):  
Coupling Effect ◽  
Experimental Results ◽  
Mode Shapes ◽  
Experimental Investigations ◽  
Coupling Effects ◽  
Symmetry Approach ◽  
Anisotropic Elastic ◽  
Elastic Modes ◽  
Bending Modes ◽  
The One

It is known that in elastic disc-shaft systems in particular, the one-nodal-diameter mode of the discs can be highly coupled with the bending modes of the shaft. Consequently, when the system rotates, the elastic modes of the flexible discs are coupled with the gyroscopic modes of the flexible shaft equipped with rigid discs. In the paper this coupling effect is investigated numerically and experimentally.A numerical model, based on a finite element cyclic symmetry approach, is presented. This model has been developed for studying the wheel-shaft coupling effects on the global behavior of turbomachinery rotors. In order to better illustrate the phenomenon involved and to validate the model, the method is applied here to a thin tuned and detuned circular disc mounted on an elastic shaft. Related frequency and mode shapes of the rotating assembly are discussed. Additional experimental results, based on an experimental modal analysis technique for rotating structures, are presented. Both numerical and experimental results are compared.

scholarly journals Vibronic coupling in the excited-states of carotenoids

2016 ◽  
Vol 18 (16) ◽  
pp. 11443-11453 ◽  
Author(s):  
Takeshi Miki ◽  
Tiago Buckup ◽  
Marie S. Krause ◽  
June Southall ◽  
Richard J. Cogdell ◽  
...  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Vibronic Coupling ◽  
Relaxation Dynamics ◽  
Dark State ◽  
Electronic Excited States

The ultrafast femtochemistry of carotenoids is governed by the interaction between electronic excited states, which has been explained by the relaxation dynamics within a few hundred femtoseconds from the lowest optically allowed excited state S2to the optically dark state S1.

scholarly journals Herzberg-Teller Vibronic Coupling Effect on the Vibrationally-Resolved Electronic Spectra and Intersystem Crossing Rates of a TADF Emitter: 7-PhQAD

2021 ◽  
Author(s):  
Sirong Lin ◽  
Zheng Pei ◽  
Bin Zhang ◽  
Huili Ma ◽  
Wanzhen Liang
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Coupling Effect ◽  
Delayed Fluorescence ◽  
Vibronic Coupling ◽  
Time Dependent ◽  
Rate Coefficients ◽  
Quantitative Prediction ◽  
Intersystem Crossing ◽  
Triplet Energy

Assessing and improving the performance of organic light-emitting diode (OLED) materials require quantitative prediction of rate coefficients for the intersystem crossing (ISC) and reverse ISC (RISC) processes, which are determined not only by the singlet-triplet energy gap and the direct spin-orbit coupling (SOC) at a thermal equilibrium position of the initial electronic state but also by the non-Condon effects such as the Herzberg-Teller vibronic coupling (HTVC) and the spin-vibronic coupling (SVC). Here we applied the time-dependent correlation function approaches to calculate the vibronic absorption and fluorescence spectra and ISC and RISC rates of a newly synthesized multiple-resonance-type (MR-type) thermally activated delayed fluorescence (TADF) emitter, 7-phenylquinolino[3,2,1-de]acridine-5,9-dione (7-PhQAD), with inclusion of the Franck-Condon (FC), HTVC, and Duschinsky rotation effects. It is found that the experimentally-measured ISC rate of 7-PhQAD originates predominantly from the HTVC which increases the ISC rate by more than one order of magnitude while the HTVC effect on the vibronic spectra is negligible. The small discrepancy between the theoretical and experimental rates originates from the neglect of the second-order SVC and the inaccurate excited states calculated by the single-reference time-dependent density functional theory. This work provides a demonstration of what proportion of ISC and RISC rate coefficients of a MR-type TADF emitter can be covered by the contribution of HTVC, and opens design routes that go beyond the FC approximation for the future development of high-performance systems.

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