Temperature coefficients of zero‐field splittings of multiply oriented triplet states of aromatic molecules in single crystals

1975 ◽  
Vol 62 (5) ◽  
pp. 1954-1957 ◽  
Author(s):  
Mon‐Chao Chen ◽  
A. S. Cullick ◽  
Roger E. Gerkin
Keyword(s):  
Single Crystals ◽  
Zero Field ◽  
Triplet States ◽  
Aromatic Molecules ◽  
Temperature Coefficients

scholarly journals Free Induction Decay and Spin Echo Signals from Spin Triplet States of Axially Asymmetric Objects in Single Crystals in Zero Constant Magnetic Field:

2020 ◽  
Vol 5 (7) ◽  
pp. 813-821
Author(s):  
Nathalie P. Fokina ◽  
Maia O. Elizbarashvili
Keyword(s):  
Magnetic Field ◽  
Single Crystals ◽  
Constant Magnetic Field ◽  
Free Induction Decay ◽  
Spin Echo ◽  
Zero Field ◽  
Triplet States ◽  
Free Induction ◽  
Spin Triplet ◽  
Axially Asymmetric

Anisotropic dynamics of the spin triplet states (STSs) in single crystals with the zero field splitting (ZFS) of their levels by the axially asymmetric Hamiltonian is investigated in zero constant magnetic field (ZF) under the action of the canonically oriented varying magnetic fields. The equations of motion for single transition operators (STOs) corresponding to the definite transition of ZFS are derived.  The obtained equations written in terms of one averaged equation for STO vector appeared to be a particular case (for STS) of the universal equation of Feynman et al, which is valid for any kind of perturbation affecting only two levels of any quantum mechanical system. As well as that, our equation is analogous to the Bloch equation without decay for the usual magnetization components of the Zeeman system in a constant magnetic field and a transverse to it varying field. This statement is valid, if the population probabilities of the corresponding levels of STS are not artificially equalized. At that, the motion of the observable macroscopic sample magnetization, which follows from our equations, has quite different character. Here, in terms of this magnetization the signals of the free induction decay and of the two-pulse spin echo are calculated in ZF.  

scholarly journals P∩N Bridged Cu(I) Dimers Featuring Both TADF and Phosphorescence. From Overview towards Detailed Case Study of the Excited Singlet and Triplet States

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3415
Author(s):  
Thomas Hofbeck ◽  
Thomas A. Niehaus ◽  
Michel Fleck ◽  
Uwe Monkowius ◽  
Hartmut Yersin
Keyword(s):  
Quantum Yield ◽  
Decay Time ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Photo Luminescence ◽  
Delayed Fluorescence ◽  
Spin Lattice Relaxation ◽  
Zero Field ◽  
Triplet States ◽  
Spin Lattice

We present an overview over eight brightly luminescent Cu(I) dimers of the type Cu2X2(P∩N)3 with X = Cl, Br, I and P∩N = 2-diphenylphosphino-pyridine (Ph2Ppy), 2-diphenylphosphino-pyrimidine (Ph2Ppym), 1-diphenylphosphino-isoquinoline (Ph2Piqn) including three new crystal structures (Cu2Br2(Ph2Ppy)3 1-Br, Cu2I2(Ph2Ppym)3 2-I and Cu2I2(Ph2Piqn)3 3-I). However, we mainly focus on their photo-luminescence properties. All compounds exhibit combined thermally activated delayed fluorescence (TADF) and phosphorescence at ambient temperature. Emission color, decay time and quantum yield vary over large ranges. For deeper characterization, we select Cu2I2(Ph2Ppy)3, 1-I, showing a quantum yield of 81%. DFT and SOC-TDDFT calculations provide insight into the electronic structures of the singlet S1 and triplet T1 states. Both stem from metal+iodide-to-ligand charge transfer transitions. Evaluation of the emission decay dynamics, measured from 1.2 ≤ T ≤ 300 K, gives ∆E(S1-T1) = 380 cm−1 (47 meV), a transition rate of k(S1→S0) = 2.25 × 106 s−1 (445 ns), T1 zero-field splittings, transition rates from the triplet substates and spin-lattice relaxation times. We also discuss the interplay of S1-TADF and T1-phosphorescence. The combined emission paths shorten the overall decay time. For OLED applications, utilization of both singlet and triplet harvesting can be highly favorable for improvement of the device performance.

Triplet excitons in diphenylbutadiene and diphenylhexatriene single crystals by zero-field delayed fluorescence ODMR

1994 ◽  
Vol 225 (1-3) ◽  
pp. 124-130 ◽  
Author(s):  
Y. Teki ◽  
J.U. von Schütz ◽  
H. Wachtel ◽  
V. Weiss ◽  
H.C. Wolf
Keyword(s):  
Single Crystals ◽  
Delayed Fluorescence ◽  
Zero Field ◽  
Triplet Excitons

scholarly journals Mobile and Trapped Triplet States in Single Crystals of Charge Transfer Complexes

1974 ◽  
Vol 29 (8) ◽  
pp. 1216-1228 ◽  
Author(s):  
H. Möhwald ◽  
E. Sackmann
Keyword(s):  
Charge Transfer ◽  
Delayed Fluorescence ◽  
Charge Transfer Complexes ◽  
Zero Field ◽  
Triplet States ◽  
Zero Field Splitting ◽  
Triplet Energy ◽  
Molecular Arrangement ◽  
Ct Complexes ◽  
Triplet Excitons

Homogeneously doped crystals of charge transfer (CT-) complexes were grown by incorporating aromatic guest donors in host CT-crystals. The host crystals contained 1,2.4,5-tetracyanobenzene (TCNB) as acceptor and deuterated aromatic electron donors. By using such doped crystals CT complexes in a well defined configuration may be studied. The triplet states of the guest complexes were used as ESR spectroscopic probes in order to determine the molecular arrangement in the host lattice. The zero-field-splitting (ZFS) parameters, D and E, of the triplet energy traps were determined and the degree of electron derealization in the triplet state was calculated from these values. In some cases a very strong guest host interaction (multicomplex formation) was established. A method for the determination of CT-triplet energies is described (accuracy 200 cm-1) . The phosphorescence spectrum of the anthracene-TCNB complex was obtained from the delayed emission spectra of different anthracene doped CT-crystals. The vibronic structure is identical to that of anthracene, while the O-O-band of the complex is blue shifted by 600 cm-1. It is shown that the undoped anthracene-TCNB crystal exhibits P-type delayed fluorescence and that the triplet exciton diffusion in this crystal is nearly temperature independent. In the undoped biphenyl-TCNB crystal E-type delayed fluorescence originating from the thermal depopulation of the mobile triplet excitons is established. The remarkable differences of the two types of triplet excitons are interpreted in terms of the different polarity in the triplet states of the two CT-crystals.

Temperature and Solvent Dependences of the Zero-Field Splittings and Character of the Triplet States of Methylpyrazines

1994 ◽  
Vol 98 (33) ◽  
pp. 7963-7966 ◽  
Author(s):  
Tosihiro Kamei ◽  
Masahide Terazima ◽  
Seigo Yamauchi ◽  
Noboru Hirota
Keyword(s):  
Zero Field ◽  
Triplet States
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