Precision spectroscopy and laser cooling scheme of a radium-containing molecule

Abstract

Molecules containing heavy, radioactive nuclei are predicted to be extremely sensitive to violations of the fundamental symmetries of nature. Radium monofluoride molecules are of particular interest, as the nuclear octupole deformation of certain radium isotopes massively boosts their sensitivity to symmetry-violating nuclear properties. Moreover, they are predicted to be laser coolable, opening up a wide range of opportunities for precision studies. Here, we present measurements of the rovibronic structure of these molecules, which allow an unambiguous determination of their laser cooling scheme. We demonstrate an improvement in resolution of more than two orders of magnitude compared to previous studies. Our developments allowed measurements of minuscule amounts of hot molecules, with only a few hundred per second produced in a particular rotational state. The combined precision and sensitivity achieved in this work offer new opportunities for studies of radioactive molecules of interest in fundamental physics, chemistry and astrophysics.

Relativistic coupled-cluster calculations of RaOH pertinent to spectroscopic detection and laser cooling

“…[1][2][3][4] Small molecules containing radioactive elements, e.g., Ra, Ac, or Pa offer sensitive and versatile avenues for precision spectroscopy search of fundamental physics beyond the Standard Model (BSM), including the search of the electron's electric dipole moment (eEDM), nuclear magnetic quadrupole moments (nMQM), and Schiff moments. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Furthermore, Ra(I) in many molecular species has the potential to serve as efficient optical cycling centers 5,16,[22][23][24][25][26][27][28] ; such radium-containing molecules are promising candidates for the application of laser-cooling and subsequent advanced quantum control techniques. High-resolution laser spectroscopy studies of the radium monofluoride (RaF) molecule have recently been reported, 1,[28][29][30] and a laser-cooling scheme has been designed for RaF.…”

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Furthermore, Ra(I) in many molecular species has the potential to serve as efficient optical cycling centers 5,16,[22][23][24][25][26][27][28] ; such radium-containing molecules are promising candidates for the application of laser-cooling and subsequent advanced quantum control techniques. High-resolution laser spectroscopy studies of the radium monofluoride (RaF) molecule have recently been reported, 1,[28][29][30] and a laser-cooling scheme has been designed for RaF. 28 Optical mass spectroscopy detection of radium-containing molecular cations including RaOH + and RaOCH 3 + has also been reported.…”

“…High-resolution laser spectroscopy studies of the radium monofluoride (RaF) molecule have recently been reported, 1,[28][29][30] and a laser-cooling scheme has been designed for RaF. 28 Optical mass spectroscopy detection of radium-containing molecular cations including RaOH + and RaOCH 3 + has also been reported. 31 Among the radium-containing molecular species, the neutral radium monohydroxide (RaOH) molecule is of significant interest.…”