Tabletop Production and Study of Cold Radioactive Molecules

Author: Conn, Chandler Jacob

Year: 2026

Degree: Dissertation (Ph.D.)

Advisor: Hutzler, Nicholas R.

Committee Members: Filippone, Bradley W.; Okumura, Mitchio; Doré, Olivier P.; Hutzler, Nicholas R.

Option: Physics

Abstract

Radioactive molecules have remained severely understudied relative to their stable counterparts, owing to difficulties associated with their radiological hazards and limited material availabilities. Despite this, their relevancy to many fields including nuclear science, chemistry, and astronomy make them attractive prospects for precision investigations. In particular, laser-coolable radioactive molecules containing octupole-deformed nuclei such as radium monohydroxide (RaOH) and radium monofluoride (RaF) promise dramatic sensitivity increases for experiments aiming to measure new physics originating from fundamental symmetry violations. Before they may be used for any of these purposes, however, new tools are needed that allow for their safe and precise study while making them accessible in a university (or similar) setting. In this thesis, we construct a tabletop cryogenic apparatus capable of studying radioactive molecules which we produce in-situ from trace quantities of starting material. We use this apparatus to perform the first spectroscopic observation of a radium-containing polyatomic molecule RaOH and its deuterated isotopologue RaOD, as well as high-resolution spectroscopy of the photon cycling transitions in RaF. To prepare for laser cooling, we develop a protocol to measure the vibrational branching ratios of these exotic species and use it to establish RaF to be among the most laser-coolable molecules known as of yet. We demonstrate the versatility of our approach by producing and detecting over twenty different atoms and molecules, ranging from transuranic radioisotopes to complex asymmetric top molecules. The species-agnostic methodology employed throughout this work allows its application to a wide class of previously ignored radioactive atoms and molecules, and makes them accessible to the many advanced experimental techniques already leveraged in stable systems.