Magnetic Resonance Spectroscopy

Abstract

The electronic and vibronic states investigated so far were obtained from the Schrödinger equation where the Hamiltonian included only electronic and lattice contributions. Whether the atoms on the lattice sites have a magnetic moment or not was irrelevant since the latter does not contribute to the total energy of the system. The situation is different if a magnetic field is applied or if the interaction of the magnetic moments with the internal magnetic field is considered. In this case magnetically degenerate electronic states will split and new transitions become possible. As a consequence the response function will change. For magnetic fields in the conventional range the new transition energies are below the energy of FIR light, which means microwaves or even high-frequency fields are appropriate for the excitation. Since the magnetic moments of the atoms or molecules are immediately related to their spin or to the paramagnetism the investigation of these transitions is called magnetic resonance or spin resonance spectroscopy. The magnetic moments of interest can originate either from the electrons or from the nuclei.