Preparation of ultracold ions in strong magnetic field and application to gas-phase NMR spectroscopy II

This paper presents a gas-phase nuclear magnetic resonance (NMR) apparatus, which may enable a tandem combination with an ion cyclotron resonance mass spectrometer. The NMR technique is widely used for analyzing the physical and chemical properties of materials; however, it is mostly limited to materials in condensed phases. Here, we construct a gas-phase NMR apparatus to extend this technique to gas-phase molecular ions. We outline the principle of NMR detection based on a Stern-Gerlach-type experiment and describe the experimental procedures and results for the preparation and manipulation of ultracold ions, which are fundamental for the proposed NMR detection. The development of the gas-phase NMR probe and radio-frequency excitation system and the features of the apparatus are presented. We also discuss the feasibility of combining this apparatus with an ion cyclotron resonance cell for realizing an NMR apparatus for mass-selected molecular ions briefly. [Display omitted] •Development of gas-phase nuclear magnetic resonance (NMR) apparatus for mass-selected molecular ions.•Tandem use of ion cyclotron resonance (ICR) mass spectrometer and NMR spectrometer.•Preparation of ultracold ions using velocity selection and velocity dispersion compensation methods.•Detection of gas-phase NMR signal by monitoring a spatial nuclear spin polarization induced via selective π-pulse excitations.