Getting to Know Manganese Acetate

Lea Vacca

Advisor: Dr. Beth Parks

Manganese acetate exhibits tunneling and has several other properties that make it unique and important to physicists. The manganese oxide core contains a huge net spin of 10, giving manganese acetate 21 energy levels. In addition, the manganese oxide cores are 14 Angstroms apart from each other; this large distance creates only a very weak interaction between cores, allowing for essentially identical environments. We examined the energy levels via energy absorption to gain insight into tunneling. After cooling the sample to below 15 K, most of the Mn acetate clusters will be in the ground state (+10 or –10 energy level). An electric field with a range of frequencies is created when a femtosecond laser pulse is incident on a silicon antenna. That electric field is passed through the manganese acetate sample, and the frequencies not absorbed are transmitted through the sample and are incident on a silicon antenna detector. These frequencies are measured by sampling different components of the transmitted electric field. The frequencies absorbed by the sample are the energies required for the Mn acetate clusters to jump from the ground state to the ±9 energy level. While past experiments have reported an absorption at ~300.6 GHz with broadening of about 5.5 GHz, all data was gained using manganese acetate crystals pressed into a pellet. It is suggested that defects in the crystal causes the broadening of frequencies. We have completed the same experiment using manganese acetate in powder form, to prevent any imposed defects, which might occur during the pellet forming process. Our results seem to be fairly consistent with the results found using the pressed pellet.