Characterization of the light induced excited spin state of a heterometallic FePt 2 complex by high-field Mössbauer spectroscopy

In order to study the interaction of light with iron containing complexes we have built a dedicated sample holder based on fiber optics, which allows exposing iron containing samples with external light sources during Mossbauer spectroscopic experiments both at low temperatures down to T = 4.2 K and high fields up to B = 5 T. With this set-up it was possible to study light induced spin state trapping (LIESST) of a heterometallic trinuclear FePt2 spin crossover (SCO) complex. The analysis of the field dependent Mossbauer spectra obtained at 4.2 K under illumination with red laser light at 635 nm shows the presence of a LIESST state with a zero field splitting of D = 5.3 cm − 1 and a rhombicity parameter of E/D = 0.14.