Light-induced electron localization in molecular metal ET4K[Fe(CN)5NO]2 with photochromic nitroprusside anion

Quasi-2D molecular metal ET4K[Fe(CN)5NO]2 with photochromic nitroprusside (NP) anion Fe(CN)5NO2− in the insulating layers was studied by ESR. Irradiation with the 514.5 nm laser light at 50 K results in reversible changes in ESR spectra: two additional ESR signals D1 and D2 from localized magnetic moments appears. After annealing at 280 K both the D1 and D2 signals disappear. The g-value of signal D1 agrees closely with g-value of ESR signal from ET layers, indicating electron localization in the ET layers. It is suggested that the reversible light-induced electron localization in the ET layers is due to interaction of ET cations with randomly distributed light-induced metastable states of the NP anions.