Electron spin polarization transfer from excited triplet porphyrins to a nitroxide radical via a spin exchange mechanism

Jun Ichi Fujisawa; Kazuyuki Ishii; Yasunori Ohba; Masamoto Iwaizumi; Seigo Yamauchi

doi:10.1021/j100047a006

Electron spin polarization transfer from excited triplet porphyrins to a nitroxide radical via a spin exchange mechanism

Jun Ichi Fujisawa, Kazuyuki Ishii, Yasunori Ohba, Masamoto Iwaizumi, Seigo Yamauchi

Division of Measurements

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Abstract

CIDEP mechanisms in systems of excited triplet tetraphenylporphyrins (MTPP; M = H₂, Mg, Zn, Cd) and TEMPO were studied by time-resolved EPR. It was found that dominant polarizations generated on TEMPO are net emissions for H₂TPP and MgTPP and net absorptions for ZnTPP and CdTPP, which are the same as the polarizations of the corresponding triplet (T₁) porphyrins. The polarizations were diminished with a spin-lattice relaxation time of TEMPO. A polarized T₁ signal of ZnTPP was observed in paraffin solution and was quenched by TEMPO. These facts clearly indicate that these polarizations are due to an electron spin polarization transfer mechanism. This is the first definitive demonstration of ESPT in triplet-doublet systems.

Original language	English
Pages (from-to)	17082-17084
Number of pages	3
Journal	Journal of physical chemistry
Volume	99
Issue number	47
DOIs	https://doi.org/10.1021/j100047a006
Publication status	Published - 1995 Jan 1

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Engineering(all)
Physical and Theoretical Chemistry

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title = "Electron spin polarization transfer from excited triplet porphyrins to a nitroxide radical via a spin exchange mechanism",

abstract = "CIDEP mechanisms in systems of excited triplet tetraphenylporphyrins (MTPP; M = H2, Mg, Zn, Cd) and TEMPO were studied by time-resolved EPR. It was found that dominant polarizations generated on TEMPO are net emissions for H2TPP and MgTPP and net absorptions for ZnTPP and CdTPP, which are the same as the polarizations of the corresponding triplet (T1) porphyrins. The polarizations were diminished with a spin-lattice relaxation time of TEMPO. A polarized T1 signal of ZnTPP was observed in paraffin solution and was quenched by TEMPO. These facts clearly indicate that these polarizations are due to an electron spin polarization transfer mechanism. This is the first definitive demonstration of ESPT in triplet-doublet systems.",

author = "Fujisawa, {Jun Ichi} and Kazuyuki Ishii and Yasunori Ohba and Masamoto Iwaizumi and Seigo Yamauchi",

year = "1995",

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TY - JOUR

T1 - Electron spin polarization transfer from excited triplet porphyrins to a nitroxide radical via a spin exchange mechanism

AU - Fujisawa, Jun Ichi

AU - Ishii, Kazuyuki

AU - Ohba, Yasunori

AU - Iwaizumi, Masamoto

AU - Yamauchi, Seigo

PY - 1995/1/1

Y1 - 1995/1/1

N2 - CIDEP mechanisms in systems of excited triplet tetraphenylporphyrins (MTPP; M = H2, Mg, Zn, Cd) and TEMPO were studied by time-resolved EPR. It was found that dominant polarizations generated on TEMPO are net emissions for H2TPP and MgTPP and net absorptions for ZnTPP and CdTPP, which are the same as the polarizations of the corresponding triplet (T1) porphyrins. The polarizations were diminished with a spin-lattice relaxation time of TEMPO. A polarized T1 signal of ZnTPP was observed in paraffin solution and was quenched by TEMPO. These facts clearly indicate that these polarizations are due to an electron spin polarization transfer mechanism. This is the first definitive demonstration of ESPT in triplet-doublet systems.

AB - CIDEP mechanisms in systems of excited triplet tetraphenylporphyrins (MTPP; M = H2, Mg, Zn, Cd) and TEMPO were studied by time-resolved EPR. It was found that dominant polarizations generated on TEMPO are net emissions for H2TPP and MgTPP and net absorptions for ZnTPP and CdTPP, which are the same as the polarizations of the corresponding triplet (T1) porphyrins. The polarizations were diminished with a spin-lattice relaxation time of TEMPO. A polarized T1 signal of ZnTPP was observed in paraffin solution and was quenched by TEMPO. These facts clearly indicate that these polarizations are due to an electron spin polarization transfer mechanism. This is the first definitive demonstration of ESPT in triplet-doublet systems.

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Electron spin polarization transfer from excited triplet porphyrins to a nitroxide radical via a spin exchange mechanism

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