Measurement of spin-lattice relaxation times of triplet states in fluid solution

1974 ◽  
Vol 29 (4) ◽  
pp. 616-617 ◽  
Author(s):  
P.W. Atkins ◽  
A.J. Dobbs ◽  
K.A. McLauchlan
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Triplet States ◽  
Fluid Solution ◽  
Spin Lattice

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.

An electron spin resonance and CIDEP study of the primary processes in the photoreductions of furaldehyde, furyl methyl ketone, and acetylthiophene by phenols

1981 ◽  
Vol 59 (1) ◽  
pp. 116-122 ◽  
Author(s):  
Kuang S. Chen ◽  
Jeffrey K. S. Wan
Keyword(s):  
Double Bond ◽  
Methyl Ketone ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Triplet States ◽  
Time Resolved ◽  
Spin Lattice ◽  
Carbon Double Bond ◽  
Photochemical Systems

The primary processes in the photoreduction of 2-furaldehyde, 2-furyl methyl ketone, and 2-acetylthiophene by phenol, 2,6-di-tert-butylphenol, and pentachlorophenol, respectively, were studied by esr and time-resolved CIDEP techniques. These furan derivatives, in their excited triplet states, can abstract a hydrogen atom from phenol via either the carbonyl group or the carbon–carbon double bond. The present results suggest that they all behave in the primary processes predominantly as carbonyl compounds. The spin–lattice relaxation times of all transient and polarized radicals observed in these photochemical systems were estimated by the CIDEP technique. The photoreductions of furaldehyde and furyl methyl ketone were also examined by high-field CIDNP. The nuclear polarization is mainly due to the cage products and the results are consistent with triplet carbonyl abstraction mechanism. Secondary radical addition to the carbon–carbon double bond of the furan ring was also observed in the furaldehyde–phenol system.

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.

2021 ◽  
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(PN)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 varies 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.

Analysis of Spin Polarisation Transients in Periodically Photo-excited Triplet States

1975 ◽  
Vol 30 (5) ◽  
pp. 571-582 ◽  
Author(s):  
C. J. Winscom
Keyword(s):  
Lattice Relaxation ◽  
Rectangular Pulse ◽  
Decay Rates ◽  
Spin Lattice Relaxation ◽  
Pulse Excitation ◽  
Triplet States ◽  
Relaxation Rates ◽  
Spin Sublevel ◽  
Spin Lattice ◽  
The Individual

Abstract The behaviour of spin sublevel populations with time following periodic photo-excitation is ex-amined. The treatment is limited to conditions of magnetic field strength and temperature for which the spin lattice relaxation rates dominate the individual spin sublevel decay rates. The response of the system to three modes of excitation is considered: (i) continuous excitation using a time-independent intensity (ii) periodic rectangular pulse excitation and (iii) periodic waveform excitation. A convenient correspondence between the various forms of solutions is pointed out. The requirements of an experiment to determine spin-lattice relaxation rates in organic triplets at 77 K are discussed.

Bonded Hydrogen and Trapped H2 in a-Si1−xGex:H Alloys

1989 ◽  
Vol 149 ◽  
Author(s):  
E. J. Vanderheiden ◽  
G. A. Williams ◽  
P. C. Taylor ◽  
F. Finger ◽  
W. Fuhs
Keyword(s):  
Temperature Dependence ◽  
Molecular Hydrogen ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
H Nmr ◽  
Local Environments

ABSTRACT1H NMR has been employed to study the local environments of bonded hydrogen and trapped molecular hydrogen (H2) in a series of a-Si1−xGex:H alloys. There is a monotonic decrease of bonded hydrogen with increasing x from ≈ 10 at. % at x = 0 (a-Si:H) to ≈ 1 at. % at x = 1 (a-Ge:H). The amplitude of the broad 1H NMR line, which is attributed to clustered bonded hydrogen, decreases continuously across the system. The amplitude of the narrow 1H NMR line, which is attributed to bonded hydrogen essentially randomly distributed in the films, decreases as x increases from 0 to ≈ 0.2. From x = 0.2 to x ≈ 0.6 the amplitude of the narrow 1H NMR line is essentially constant, and for x ≥ 0.6 the amplitude decreases once again. The existence of trapped H2 molecules is inferred indirectly by their influence on the temperature dependence of the spin-lattice relaxation times, T1. Through T1, measurements it is determined that the trapped H2 concentration drops precipitously between x = 0.1 and x = 0.2, but is fairly constant for 0.2 ≤ x ≤ 0.6. For a-Si:H (x = 0) the H2 concentration is ≈ 0.1 at. %, while for x ≥ 0.2 the concentration of H2 is ≤ 0.02 at. %.

Water-Saturated Mesoporous MCM-41 Systems Characterized by 1H NMR Spin-Lattice Relaxation Times

1995 ◽  
Vol 99 (12) ◽  
pp. 4148-4154 ◽  
Author(s):  
Eddy Walther Hansen ◽  
Ralf Schmidt ◽  
Michael Stoecker ◽  
Duncan Akporiaye
Keyword(s):  
1H Nmr ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Water Saturated ◽  
Mcm 41
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