Femtosecond optical pump-probe reflectivity studies of spin-state photo-switching in the spin-crossover molecular crystals [Fe(PM-AzA)2(NCS)2]

Andrea Marino (1) , Marina Servol (1) , Roman Bertoni (1) , Maciej Lorenc (1) , Cindy Mauriac (2) , Jean-François Letard (2) , Eric Collet (1)

1 IPR - Institut de Physique de Rennes
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

We report here on the ultrafast photo-switching dynamics of a Fe(II) molecular material [Fe(PM-AzA)2(NCS)2]. It undergoes a thermal spin-crossover which can be detected by magnetic measurements or by optical reflectivity. We use here femtosecond optical reflectivity to study the ultrafast photo-switching dynamics. Our results indicate that the HS state is reached from the LS state within less than 100 fs, through an intermediate MLCT state. This ultrafast relaxation from the electronic excited state towards the structurally relaxed HS state is followed by a vibrational cooling of the hot HS molecules within ≈1 ps timescale.

Mots clés: Spin crossover; Femtochemistry; LIESST; Phase transitions; Laser spectroscopy

Domaines: Chimie de coordination

Andrea Marino, Marina Servol, Roman Bertoni, Maciej Lorenc, Cindy Mauriac, et al.. Femtosecond optical pump-probe reflectivity studies of spin-state photo-switching in the spin-crossover molecular crystals [Fe(PM-AzA)2(NCS)2]. Polyhedron, 2013, 66, pp.123-128. ⟨10.1016/j.poly.2013.03.009⟩. ⟨hal-00904690⟩