Issue 30, 2015

Femtosecond spin-state photo-switching dynamics in an FeIII spin crossover solid accompanied by coherent structural vibrations

Abstract

We investigate light-induced excited spin-state trapping (LIESST) dynamics of an FeIII spin-crossover material from low (S = 1/2) to high (S = 5/2) spin states. Our results show that this process occurs only at the molecular level as evidenced by the linear dependence of the fraction of photo-switched molecules with the excitation density as well as with the initial fraction of low spin molecules. The inter-system crossing from photoexcited LS (S = 1/2) to HS (S = 5/2) occurs within ≈200 fs and is accompanied by coherent non-equilibrium vibrational relaxation in the photo-induced HS state. These results reveal similar dynamical features to those already reported for LIESST in FeII systems. The activation of coherent molecular vibrations is essential for rapidly reaching the HS potential on the timescale of molecular motions, whereas their fast damping allows an efficient trapping in the HS potential. The observed coherent oscillations are attributed to photoinduced molecules in the HS states, as supported by Raman spectroscopy at thermal equilibrium, and DFT analyses of molecular vibrations and TD-DFT calculations of optical absorption.

Graphical abstract: Femtosecond spin-state photo-switching dynamics in an FeIII spin crossover solid accompanied by coherent structural vibrations

Supplementary files

Article information

Article type
Communication
Submitted
27 Mar 2015
Accepted
05 May 2015
First published
06 May 2015

J. Mater. Chem. C, 2015,3, 7792-7801

Author version available

Femtosecond spin-state photo-switching dynamics in an FeIII spin crossover solid accompanied by coherent structural vibrations

R. Bertoni, M. Lorenc, J. Laisney, A. Tissot, A. Moréac, S. F. Matar, M.-L. Boillot and E. Collet, J. Mater. Chem. C, 2015, 3, 7792 DOI: 10.1039/C5TC00854A

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