Cooperative relaxation of the metastable states in the photomagnetic octacyanotungstate CsI[{CoII(3-CN-py)2}{WV(CN)8}] · H2O

Rémy Le Bris (1) , Corine Mathonière (1) , Jean-François Létard (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

The metastable states of the Cs[{Co(3-cpy)2}{W(CN)8}] .H2O (3-cpy = 3-cyanopyridine) complex,, characterized by a CTIST phenomenon with a high-temperature phase formed by CoIIHS (S = 3/2)-NC-WV (S = 1/2) units and a low-temperature phase formed by CoIIILS (S = 0)-NC-WIV (S = 0) units, have been induced at low temperature either by thermal quenching (RC state) or by irradiation (PI state). The T(TIESST) and T(LIESST) relaxation temperatures of RC and PI states, respectively, have been determined and the incompleteness of photo-excitation discussed. The presence of sigmoidal kinetics and the observation of LITH hysteresis loop under irradiation demonstrate the cooperative nature of the relaxation. The thermodynamic parameters have been determined and a simulation of the T(TIESST) curve done.

Mots clés: Metastable states; Relaxation; LIESST; T(LIESST); T(TIESST); chemical compound; Octacyanotungstate; Photomagnetism

Domaines: Matériaux

Rémy Le Bris, Corine Mathonière, Jean-François Létard. Cooperative relaxation of the metastable states in the photomagnetic octacyanotungstate CsI[{CoII(3-CN-py)2}{WV(CN)8}] · H2O. Chemical Physics Letters, 2006, 426 (4-6), pp.380-386. ⟨10.1016/j.cplett.2006.05.086⟩. ⟨hal-00090429⟩