Patent ID: 6906322

Claim:
A charged particle source for preparing secondary electrically charged droplets having a selected size both from a liquid sample, containing chemical species in a solvent, carrier liquid or both, said source comprising: a) an electrically charged droplet source for generating a primary electrically charged droplet of the liquid sample in a flow of bath gas, wherein said primary electrically charged droplet has a selected droplet exit time and a momentum substantially directed along a droplet production axis; b) a charged droplet trap in fluid communication with the electrically charged droplet source and positioned along said droplet production axis at a selected distance downstream from said electrically charged droplet source, with respect to the flow of bath gas, for receiving the flow of bath gas and primary electrically charged droplet; wherein the primary electrically charged droplet remains in the charged droplet trap for a selected residence time sufficient to provide partial evaporation of solvent, carrier liquid or both from the primary electrically charged droplet generating at least one secondary electrically charged droplet having said a selected size; wherein the secondary electrically charged droplets having said a selected size exit the trap along an ion production axis at a selected release time; and c) at least one flow inlet in fluid communication with said charged droplet source for introducing a flow of bath gas.