THEORETICAL STUDY OF ThO AND HfF+ FOR ELECTRON ELECTRIC DIPOLE MOMENT SEARCH EXPERIMENTS

Visible and ultraviolet laser spectroscopy of ThF

“…The most significant advantage of ThF + is that the eEDM sensitive state ( 3 ∆ 1 , v + = 0, J + = 1) of ThF + is the electronic ground state [7,8], which means, in principle, that the ESR spectroscopy could exploit a very long coherence time. Furthermore, the effective electric field of ThF + (35.2 GV/cm [9]) is 50% larger than that of HfF + (24 GV/cm [10,11]), which promises a factor of 35.2/24=1.5 times increase of the eEDM sensitivity. Beyond measuring the eEDM, 229 ThF + may also be a good candidate for determining the parityforbidden Nuclear Magnetic Quadrupole Moment (NMQM), due to the large nuclear deformation of 229 Th [12,13].…”

Spectroscopy on the eEDM-sensitive states of ThF$^+$

“…Sensitivity to the eEDM depends on three main factors in the experiment: (i) effective electric field strength that couples to the eEDM, (ii) coherent interrogation time of the eEDM-sensitive state, and (iii) total number of counts in the experiment for statistics. Groups with the world's best limits on the eEDM [14][15][16] take advantage of the large effective electric field [17][18][19][20][21][22][23] in molecules to enhance their eEDM sensitivities. One of the ingredients for success in ACME [15,24] and Imperial College [16] experiments is the large number of molecules that they probe in their neutral molecular beam experiments.…”

“…The latter keeps all the benefits of using molecular ions in an ion trap, and it also boasts a larger effective electric field and longer coherence times than the former [18][19][20][21]26], both of which promise a direct increase in the eEDM sensitivity. Previous spectroscopic work [26][27][28][29] shows that we can use similar experimental techniques across both molecular species, including multi-state detection [25,30].…”