We investigated the quantum beats, the oscillation between singlet and triplet states of radical pairs induced by the microwave field resonant to one of the component radicals. They were observed as the alternation of the yields of the component radicals by a nanosecond time-resolved optical absorption with the X-band (9.15 GHz) resonant microwave pulse. This technique was applied to the photochemical reaction of benzophenone, benzophenone-d(10), and benzophenone-carbonyl-(13)C in a sodium dodecylsulfate micellar solution with a step-by-step increase of the resonant microwave pulse width. The yields of the component radicals showed alternation with an increase of the microwave pulse width. This indicates that the radical pair retains spin coherence in the micellar solution. The magnetic isotope effect on the amplitude of the quantum beat was observed. The MW effect on the quantum beat of BP-(13)C decreases from 80% to 60% of that of BP by irradiation of the pi-pulse MW due to spin-locking. The kinetic parameters were also determined using the X- or Ku-band (17.44 GHz) region. They are almost similar to each other except for the intersystem recombination rate in the system of BP-(13)C, which may be slightly higher than those in other systems.
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http://dx.doi.org/10.1021/jp076611w | DOI Listing |
Soft Matter
January 2025
School of Chemistry and University of Sydney Nano Institute, The University of Sydney, Sydney, NSW, 2006, Australia.
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January 2025
College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China.
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January 2025
Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India.
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Unilever R&D, 40 Merrit Boulevard, Trumbull, Connecticut 06611, United States.
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View Article and Find Full Text PDFSmall
January 2025
Department of Chemistry, McGill University, 801, Sherbrooke St. West, Montreal, QC, H3A 0B8, Canada.
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