Moessbauer studies of the vibrational anisotropy and of light-induced metastable states in single-crystalline guanidinium nitroprusside

Moessbauer studies in the energy and time domain were performed on single crystals of guanidinium nitroprusside with different orientations of their crystallographic a-, b- and c-axes with respect to the incident radiation. A remarkable anisotropy of the Lamb-Moessbauer factor is observed. Metastable states of the nitroprusside anion were populated by means of incoherent irradiation from light-emitting diodes. Calculated hyperfine parameters for the ground state and for the excited states have been retrieved from density functional calculations