Femtosecond Spin-State Switching Dynamics of Fe(II) Complexes Condensed in Thin Films.
/ Authors
Lea Kämmerer, Gérald Kämmerer, Manuel Gruber, Jan Grunwald, T. Lojewski, L. Mercadier, L. Le Guyader, R. Carley, C. Carinan, N. Gerasimova
and 15 more authors
D. Hickin, B. V. Van Kuiken, Giuseppe Mercurio, M. Teichmann, S. Kuppusamy, A. Scherz, Mario Ruben, K. Sokolowski-Tinten, A. Eschenlohr, K. Ollefs, C. Schmitz-Antoniak, F. Tuczek, P. Kratzer, U. Bovensiepen, H. Wende
/ Abstract
The tailoring of spin-crossover films has made significant progress over the past decade, mostly motivated by the prospect in technological applications. In contrast to spin-crossover complexes in solution, the investigation of the ultrafast switching in spin-crossover films has remained scarce. Combining the progress in molecule synthesis and film growth with the opportunities at X-ray free-electron lasers, we study the photoinduced spin-state switching dynamics of a molecular film at room temperature. The subpicosecond switching from the S = 0 low-spin ground state to the S = 2 high-spin state is monitored by analyzing the transient evolution of the Fe L3 X-ray absorption edge fine structure, i.e. element-specifically at the switching center of the Fe(II) complex. Our measurements show the involvement of an intermediate state in the switching. At large excitation fluences, the fraction of high-spin molecules saturates at ≈50%, which is likely due to molecule-molecule interaction within the film.
Journal: ACS nano