Spectroscopic Studies of Magnetic Properties and Spin-Phonon Couplings in Metal Complexes

Single-molecule magnets (SMMs) are of intense interest due to their potential use as molecular data storage. However, much is yet to be understood about the magnetic transitions that govern their properties, including how to control the relaxation from one bistable magnetic ground state to another. The primary focus of this dissertation is the use of far-IR and Raman spectroscopies to probe magnetic excitations in SMMs. These studies serve two purposes: (1) To directly determine the energies of magnetic levels in SMMs; (2) Reveal the presence of spin-phonon couplings and quantify their magnitudes. Such studies have been performed for several compounds in this work, including transition metal and lanthanide complexes of varying symmetries. Each compound was spectroscopically studied with the application of magnetic fields, allowing the direct viewing of changes in energy levels of magnetic origin. As the magnetic peaks shift, they interact with neighboring phonons in the form of avoided crossings, indicating these states are coupled. In several cases, the results agree well with inelastic neutron scattering (INS) studies of the same compounds. In addition, DFT phonon calculations of several compounds and magnetic susceptibility measurements have been performed. These studies aim to provide a more complete understanding of the magnetic properties in several transition metal and lanthanide compounds.