Proton–electron mass ratio by high-resolution optical spectroscopy of ion ensembles in the resolved-carrier regime

Abstract

Optical spectroscopy in the gas phase is one of the key tools for the elucidation of the structure of atoms and molecules and their interaction with external fields. The line resolution is usually limited by a combination of first-order Doppler broadening due to particle thermal motion and of a short transit time through the excitation beam. For trapped particles, suitable laser cooling techniques can lead to strong

Rotational action spectroscopy of trapped molecular ions

“…The resulting angular momentum of these spins then couples with N to form the total angular momentum F 149 . Experiments by Schiller and coworkers pursue the spectroscopy of this ion by sympathetic cooling inside a Coulomb crystal of laser-cooled atomic ions (Be + ), all confined in a linear Paul trap [150][151][152] . By this approach, kinetic temperatures as low as approximately 10 mK are achieved for the molecular ions.…”

Ultracold $^{88}\rm{Sr}_2$ molecules in the absolute ground state

“…Molecules serve as natural test beds for molecular quantum electrodynamics [1][2][3][4], in addition to tests of beyond-Standard-Model physics such as searches for T -symmetry violation [5][6][7][8][9][10], dark matter [11][12][13], time variation of fundamental constants [14][15][16][17][18], and non-Newtonian gravity [19]. In this regard, alkaline-earth-metal molecules represent an exciting frontier since their closed-shell structure lead to 1 Σ ground potentials that are naturally insensitive to external perturbations.…”

Precision spectroscopy of the hydrogen molecular ions: present status of theory and experiment

“…In recent years substantial progress in the precision spectroscopy of the HD + molecular ion through Dopplerfree spectroscopy of ultracold trapped ions in the Lamb-Dicke regime [1,2,3] has been achieved. This conference proceedings contribution has a threefold interest: we want to present an analysis of the obtained experimental data and to infer from it the new value of the reduced mass of the two nuclei: m p m d /(m p + m d ) normalized to the electron mass.…”