OVERVIEW — Precise measurements of atomic structure in Group III and IV atoms
A century ago, the hydrogen atom became a testing ground for the new theory of quantum mechanics. However, in any atomic system beyond hydrogen, approximation techniques are required for quantitative tests. Recently, particular heavy atomic species have become important in searching for the type of physics usually associated with accelerators and elementary particle physics.
Precise, ab initio determination of atomic wavefunctions in these complicated atoms present a significant challenge to state-of-the-art atomic theory calculations. Yet any atomic test of elementary particle physics rely critically on accurate atomic theory, which is essential to distinguish the complicated quantum mechanics from the more ‘fundamental’ physics that is being targeted. There is a long history of ever-improving atomic theory and corresponding precise measurements of atomic properties in the single-valence alkali systems. In our lab we focus on the somewhat more complicated three-valence-electron systems in Group III (thallium, indium, ….), and more recently Group IV lead atoms, for which there is significantly less experimental data.
Thus, at Williams, we are pursuing a series of related high-precision experiments in which semiconductor diode lasers are used to probe these multi-valence atoms. Atomic samples are contained in heated quartz vapor cells and also in an atomic beam apparatus. First, these experiments test the accuracy and guide the refinement of the cutting-edge atomic theory work. Second, we can use similar techniques to design experiments that explicitly search for physics of (and beyond) the Standard Model of elementary particle physics.
Key aspects of these ‘precision measurements’ include careful experimental design, laser stabilization techniques, and various sophisticated signal processing and analysis techniques, including FM spectroscopy, precision polarimetry, and lots and lots of lock-in detection. These measurements have been completed in collaboration with over sixty Williams undergraduate students as well as seven postdoctoral research associates over the past two decades.
We are grateful for the generous funding of: