We propose to map out magnetic and lattice excitations in compounds Mn(5-x)Fe(x)Si3.Varying the Fe content, the system shows a tunable magneto-caloric effect, both in the magnetic entropy change as well as in the temperature range. We have recently shown, that magnetism and lattice are coupled dynamically as evidenced by anisotropic changes in the lattice expansion and the elastic constants upon crossing the Curie temperature Tc. Furthermore this compound also follows the recently suggested paradigm that a large magneto-caloric effect is promoted by different crystallographic sites occupied by the magnetic ions. In particular we would like to study in this experiment the system with x=2, where one site is nearly completely occupied by Mn and the other by Fe. In detail we would like to map out the excitation spectrum of a single crystal at temperatures T=10K and T=100 K.