LMI Seminar: Searching for parity violation in trapped chiral molecular ions

Abstract:

Molecules are called chiral when they have two non-superimposable spatial configurations called enantiomers, which are mirror images of each other. Experimentally comparing left- and right-handed enantiomers is a powerful way to isolate forces that are parity-violating (PV). Within the Standard Model the PV nuclear weak force is predicted to make one enantiomer slightly more stable than the other, but the method can be used to detect other PV new physics forces. We are building trapped ion version of the search using CHDBrI+ to detect PV in chiral molecules for the first time. Precision spectroscopy of such complex polyatomic molecular ions requires both cold generation and state-selective detection to be developed.

To this end, we have developed cold preparation of CHDBrI+ through Rydberg assisted near-threshold ionization in the VUV range demonstrating that the initial vibrational state of the molecule can be selected. For detection we have connected a velocity map imaging detector to our ion trap. Using this apparatus, we will probe the molecular internal state populations using photofragment velocity measurements. We have now completed the commissioning of the ion trap-VMI with laser cooled Yb+, which will be used for the sympathetic collisional cooling of co-trapped CHDBrI+ for the precision measurement.

Interestingly, due to the sensitivity of velocity measurements, we are able to observe the transition liquid-gas transition in trapped ions for the first time. We track the entire process using the response of the ion velocity spread to the RF field of the trap. The direct velocity measurements reveal that short-range order, marking the onset of the liquid phase, emerges at a higher temperature than any spatial features by which the liquid becomes visible in fluorescence imaging.

We will discuss our progress on all these topics as well possible searches for BSM with chiral molecular ions. 

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