Abstract:
Accurate molecular spectroscopy in the mid-infrared region allows precision measurements with applications fundamental physics. The weak nuclear force should cause parity violating frequency shifts between the rovibrational spectra of two enantiomers of a chiral molecule. However, these small effects have never been observed. The measurement of PV in molecules is interesting for a range of subjects across the board from biomolecular homochirality to tests of the standard model. We will present our on-going work towards developing the technologies needed for this precision spectroscopic measurement. We have been working towards measuring this difference using Ramsey interferometry in the mid-infrared (at around 10 µm) using ultra-narrow linewidth CO2 lasers referenced to atomic clocks in Paris via an optical link.
We present the results of preliminary investigations conducted on methyltrioxorhenium (MTO), an achiral test molecule from which promising chiral derivatives have recently been synthesized. This work has enabled us to identify several key elements of the current experiment needing improvement prior to making a PV measurement.
The first is the lack of tuneability of our CO2 lasers. We present our on-going work towards their replacement with quantum cascade lasers (QCLs), the very latest mid-infrared laser technology which offers broad and continuous tuning. Secondly, our current molecular beam source only yields a modest flux for species such as MTO and its chiral derivatives which are solid at room temperature. We plan to overcome this by developing a buffer-gas-beam source and report on our latest efforts to implement buffer-gas cooling on polyatomic species such as MTO.
Laboratoire de Physique des Lasers, CNRS, Université Paris 13, Sorbonne Paris Cité, Villetaneuse, France