Characteristics of a charged-droplet beam generated by vacuum electrospray of an ionic liquid

► Charged-droplet beam was generated by vacuum electrospray of an ionic liquid. ► Target current exceeding 200 nA was produced with a low flow rate of 0.05 μL/min. ► The m/z values of emitted charged particles were investigated by a TOF technique. ► The m/z values proved to decrease with decreasing flow rate of the ionic liquid. ► Masses, charge numbers and radii of the emitted charged droplets were examined.