Linear and circular dichroism detection of magnetic torque on matrix isolated small manganese clusters

Matrix isolated atoms and small manganese clusters have been isolated in krypton matrices at concentrations lower than 10^?3. Absorption and polarized light measurements have been conducted simultaneously on these samples. Defined electronic transitions show distinct circular or linear dichroïsm signals only after the application of an external magnetic field. Clusters belonging to these bands have an axial structure with a plane of symmetry perpendicular to their magnetic moment. On the basis of previous ESR results we are concluding that three of the defined electronic transitions are due to Mn₅ cluster.