This award, funded by the Chemical Structure, Dynamics, and Mechanisms - A Program of the Division of Chemistry, enables Prof. Timothy C. Steimle of the Department of Chemistry, Arizona State University at Tempe to experimentally determine the most fundamental chemical behavior and properties of small metal containing molecules using new laser-based technologies. Two interrelated classes of molecules will be investigated: a) diatomic molecules containing heavy metal atoms of thorium, hafnium and ytterbium, and b) the triatomic molecules, Si3 and SiH2. Both classes of molecules exhibit vibrational and electronic motions that defy conventional theoretical description. Molecular magnetic and electric dipole moments, which are used in the proposed schemes to produce ultracold samples and are routinely predicted by theorists, will be experimentally measured from the analysis of Zeeman and Stark laser spectroscopy, respectively. The data is critical for proposed experiments that use heavy metal containing molecules (e.g. ThO, ThS and YbF) to test various extensions of the Standard Model through the detection of the electric dipole moment of the electron (eEDM) and the anapole moment of nuclei. The laser-based studies of Si3 and SiH2 will investigate the mechanism of spin-orbit and other relativistic induced coupling between electronic and vibrational motions. In collaboration with theorists, new methodologies for addressing relativistic effects will be developed and assessed. All studies will be performed in the gas-phase, which is most compatible with new theories.
Molecules containing elements near the end of the periodic table (e.g. Th, Hf, and Yb) are poorly understood and modeled compared to those at the beginning (C, O and H), yet are of great technological importance in, for example, catalysis, batteries or solar cells. Much of the unique properties of these molecules can be traced to the fact that the electrons forming the chemical bonds are accelerated to speeds approaching the speed of light. At these unusual speeds, relativistic effects become important which, in general, strengthen and shorten chemical bonds. Furthermore, it is predicted that under these relativistic conditions, here-to-fore unobserved phenomena become greatly enhanced. One such phenomenon is the interaction of the electron with the very large electric fields predicted to exist in the region of the nuclei. The data generated in this study are critical for sophisticated experiments designed to precisely measure these effects. A comparison of predicted and measured charge distribution of the electron is critical to the field of physics for validation of modern models for fundamental particles. Hence, the tiny metal containing molecules studied here are the laboratory for understanding new properties of matter, generating information typically obtained at large research facilities that possess particle accelerators, but at a small fraction of the cost.
