To explore the photo-sensitivity of 1, the sample was irradiated with white light (WL) (power: 0.5 mWcm -2 ) for ca. 180 min at 10 K. The resultant spectrum significantly differs from the spectra obtained in the dark at both 10 K and 350 K suggesting the possibility of the formation of photoinduced metastable HS Fe(II) state from the LS state of 1 at 10 K. The evolution of absolutereflectivity vs. time exhibits an increase in the absolute-reflectivity value, attaining a saturation after 15 min of WL irradiation. This value is lower than the value obtained at 350 K, which indicates an incomplete photo-induced SCO of 1 from LS state to photo-induced metastable HS at 10 K under white light irradiation. After irradiation over 180 min, the thermal stability of the photoinduced metastable HS state was also investigated by heating the sample in the dark (sweep-rate: 0.4 Kmin -1 ), which shows a decrease in the absolute-reflectivity due to the relaxation of the photoinduced HS state to diamagnetic LS ground-state where a complete relaxation was observed at around 60 K (TLIESST). The absence of a clear plateau suggests that the photo-excited state is unstable because of fast relaxation. After this temperature, the absolute-reflectivity values show similar features as observed in the dark. Additional photo-excitation at 10 K with 14 LED (1050 to 365 nm) showed that all LEDs able to populate the paramagnetic HS state in agreement with the efficiency of WL, where maximum efficiency was observed at 625 nm.