Fast photo-driven electron spin coherence transfer: The effect of electron-nuclear hyperfine coupling on coherence dephasing

Matthew D. Krzyaniak, Lukáš Kobr, Brandon K. Rugg, Brian T. Phelan, Eric A. Margulies, Jordan N. Nelson, Ryan M. Young, Michael R. Wasielewski

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Selective photoexcitation of the donor in an electron donor-acceptor1-acceptor2 (D-A1-A2) molecule, in which D = perylene and both A1 and A2 = naphthalene-1,8:4,5-bis(dicarboximide), results in sub-nanosecond formation of a spin-correlated singlet radical pair 1(D+•-A1-•-A2) having a large electron spin-spin exchange interaction, 2J, which precludes its observation by transient EPR spectroscopy. Subsequent selective photoexcitation of A1-• rapidly produces 1(D+•-A1-A2-•), resulting in a dramatic decrease in 2J, which allows coherent spin evolution to mix the singlet (S) radical pair state 1(D+•-A1-A2-•) with the T0 triplet sublevel of 3(D+•-A1-A2-•) in an applied magnetic field, where B 蠑 2J. A spin-polarized transient EPR spectrum characteristic of the spin-correlated radical pair D+•-A1-A2-• is then observed. The time delay between the two laser pulses was incremented to measure the rate of decoherence in 1(D+•-A1-•-A2) in toluene at 295 K, which was found to be 8.1 × 107 s-1. Deuteration of the perylene donor or the toluene solvent decreases the decoherence rate constant of 1(D+•-A1-•-A2) to 4.3 × 107 s-1 and 4.6 × 107 s-1, respectively, while deuteration of both the perylene donor and the toluene solvent reduced the decoherence rate constant by more than half to 3.4 × 107 s-1. The data show that decreasing electron-nuclear hyperfine interactions significantly increases the zero quantum coherence lifetime of the spin-correlated radical pair.

Original languageEnglish
Pages (from-to)7962-7967
Number of pages6
JournalJournal of Materials Chemistry C
Volume3
Issue number30
DOIs
Publication statusPublished - Aug 14 2015

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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