Shifting photo-stationary light-induced excited spin state trapping equilibrium towards higher temperature by increasing light fluence

Abstract

The Light-Induced Excited Spin-State Trapping (LIESST) process allows tuning the electronic state of spin-crossover materials from low (LS) to high spin (HS) states. The photoinduced HS state is long-lived, up to a characteristic temperature, T(LIESST), above which the system relaxes rapidly to the LS state. We study the effect of light irradiance on competing LS → HS up-conversion and HS → LS thermal relaxation on the [Fe(phen)2(NCS)2] system. Raman spectroscopy and magnetic measurements are used to investigate this phenomenon. An empiric model describes the competition between up conversion and thermal relaxation mechanisms and the stabilization of photo-stationary state towards higher temperature.