101. Hot Branching Dynamics in a Light-Harvesting Iron Carbene Complex Revealed by Ultrafast X-ray Emission Spectroscopy.
- Author
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Tatsuno H, Kjaer KS, Kunnus K, Harlang TCB, Timm C, Guo M, Chàbera P, Fredin LA, Hartsock RW, Reinhard ME, Koroidov S, Li L, Cordones AA, Gordivska O, Prakash O, Liu Y, Laursen MG, Biasin E, Hansen FB, Vester P, Christensen M, Haldrup K, Németh Z, Sárosiné Szemes D, Bajnóczi É, Vankó G, Van Driel TB, Alonso-Mori R, Glownia JM, Nelson S, Sikorski M, Lemke HT, Sokaras D, Canton SE, Dohn AO, Møller KB, Nielsen MM, Gaffney KJ, Wärnmark K, Sundström V, Persson P, and Uhlig J
- Abstract
Iron N-heterocyclic carbene (NHC) complexes have received a great deal of attention recently because of their growing potential as light sensitizers or photocatalysts. We present a sub-ps X-ray spectroscopy study of an Fe
II NHC complex that identifies and quantifies the states involved in the deactivation cascade after light absorption. Excited molecules relax back to the ground state along two pathways: After population of a hot3 MLCT state, from the initially excited1 MLCT state, 30 % of the molecules undergo ultrafast (150 fs) relaxation to the3 MC state, in competition with vibrational relaxation and cooling to the relaxed3 MLCT state. The relaxed3 MLCT state then decays much more slowly (7.6 ps) to the3 MC state. The3 MC state is rapidly (2.2 ps) deactivated to the ground state. The5 MC state is not involved in the deactivation pathway. The ultrafast partial deactivation of the3 MLCT state constitutes a loss channel from the point of view of photochemical efficiency and highlights the necessity to screen transition-metal complexes for similar ultrafast decays to optimize photochemical performance., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2020
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