Please join Yale Chemistry for a junior faculty candidate seminar in Physical Chemistry with Jacob Higgins, NRC Postdoctoral Fellow at JILA and University of Colorado Boulder.
Abstract: Optical ‘clock’ transitions within atoms and molecules have revolutionized our ability to measure time, and can be used to sense local environments in the condensed phase. Clock transitions possess narrow linewidths and can thus be measured extremely precisely, enabling access to a host of new questions ranging from fundamental physics to biology. I will discuss our team’s recent spectroscopic measurement of the low energy thorium-229 nuclear clock transition. The nuclear transition constitutes a fundamentally new kind of clock and is thought to be sensitive to fluctuations of fundamental constants. We measured the transition using vacuum ultraviolet frequency combs, which are specialized laser sources that can measure transition frequencies with high precision (in our case, ~1 kHz or ~10-8 cm-1). Thorium atoms are doped into a solid-state host crystal and are sensitive to changes in the local crystal electronic structure. Our work narrowed the transition uncertainty by roughly six orders of magnitude relative to previous measurements, making clock operation possible for the first time. We additionally studied the temperature-dependent changes to the shifts and splittings, which report on the changes in the electron density distribution and local electric field gradient experienced by the nucleus. This work represents the first steps toward building a new nuclear clock for tests of fundamental physics and demonstrates how clock-like sensors enable precise measurement of subtle changes in condensed phase environments, which is important for future sensing applications in chemistry and biophysics.
For more information on Jacob Higgin’s research: https://www.jakehigginsphd.com/research
Faculty Host: Prof. Mark Johnson