An esr and CIDEP study of the photoreduction of chromone and chromanone and their organometallic radical adducts

1984 ◽  
Vol 62 (1) ◽  
pp. 117-120 ◽  
Author(s):  
Babatunde B. Adeleke ◽  
Douglas Weir ◽  
M. Catherine Depew ◽  
Jeffrey K. S. Wan
Keyword(s):  
Hydrogen Atom ◽  
Triplet State ◽  
Spin Polarized

The esr and CIDEP results show that the photoreduction of chromones and chromanones by phenol and by triethylamine proceeds via a spin polarized T(n,π*) triplet state which abstracts a hydrogen atom from the donor. Both chromone and chromanone are found to be reactive to the addition of organometallic radicals to form some radical adducts, including organotin, organosilicon, and organogermane.

Spin-Polarized Molecular Triplet States as Qubits: Phosphorus Hyperfine Coupling in the Triplet State of Benzoisophosphinoline

2020 ◽  
Vol 11 (18) ◽  
pp. 7569-7574
Author(s):  
Joseph A. Christensen ◽  
Jiawang Zhou ◽  
Nikolai A. Tcyrulnikov ◽  
Matthew D. Krzyaniak ◽  
Michael R. Wasielewski
Keyword(s):  
Triplet State ◽  
Hyperfine Coupling ◽  
Triplet States ◽  
Spin Polarized

Radiation and Radiationless Processes in 2,3-Pentanedione; Phosphorescence Lifetime in the Gas Phase

1971 ◽  
Vol 49 (7) ◽  
pp. 987-993 ◽  
Author(s):  
A. W. Jackson ◽  
A. J. Yarwood
Keyword(s):  
Hydrogen Atom ◽  
Triplet State ◽  
Gas Phase ◽  
Ground State ◽  
Hydrogen Atom Abstraction ◽  
Intersystem Crossing ◽  
Phosphorescence Lifetime ◽  
Gaseous State ◽  
Methyl Group ◽  
Intramolecular Hydrogen

Fluorescence and phosphorescence are observed when 2,3-pentanedione in the gaseous state is excited at 365, 405, and 436°nm. The phosphorescence lifetime has been investigated as a function of temperature (298 to 363 °K) and concentration of the diketone (0.5 to 90 × 10−4 M). A mechanism that explains the experimental data is proposed. Apart from the radiative process and an intersystem crossing to the ground state, the triplet state 2,3-pentanedione molecules are removed by two other processes. One is a unimolecular reaction with a rate constant of 1 × 1011 exp (−11.0/RT) s−1 (consistent with an intramolecular hydrogen atom abstraction), and the other is an interaction with ground state molecules. The photochemistry of the triplet state of 2,3-pentanedione is compared with that of biacetyl to consider the effect of substitution of a hydrogen atom by the methyl group on the radiationless processes in diketones.

scholarly journals Spin-Polarized Oxygen Evolution Reaction Under Magnetic Field

2021 ◽  
Author(s):  
Xiao Ren ◽  
Tianze Wu ◽  
Yuanmiao Sun ◽  
Yan Li ◽  
Guoyu Xian ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Transfer ◽  
Triplet State ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Spin Exchange ◽  
Momentum Conservation ◽  
Exclusion Principle ◽  
Fast Kinetics ◽  
Spin Polarized

<p><a></a><a>The oxygen evolution reaction (OER) is the bottleneck that limits the energy efficiency of water-splitting. The process involves four electrons’ transfer and the generation of triplet state O<sub>2</sub> from singlet state species (OH<sup>- </sup>or H<sub>2</sub>O). Recently, explicit spin selection was described as a possible way to promote OER in alkaline conditions, but the specific spin-polarized kinetics remains unclear. </a><a></a><a>Here, we report that </a><a>by using ferromagnetic ordered catalysts as the spin polarizer for spin selection under </a><a></a><a>a constant magnetic field</a>, <a>the OER can be enhanced.</a> However, it does not applicable to non-ferromagnetic catalysts. We found that the spin <a>polarization occurs at the first electron transfer step in OER</a>, where <a></a><a>coherent spin exchange happens </a>between the <a></a><a>ferromagnetic</a> catalyst and the adsorbed oxygen species <a>with fast kinetics</a>, under the principle of spin angular momentum conservation. In the next three electron transfer steps, as the adsorbed O species adopt fixed spin direction, the OER electrons need to follow the Hund rule and Pauling exclusion principle, thus to carry out spin polarization spontaneously and finally lead to the generation of triplet state O<sub>2</sub>. Here, we showcase spin-polarized kinetics of oxygen evolution reaction, which gives references in the understanding and design of spin-dependent catalysts.</p>

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