Atmospheric Pressure Interface with Improved ION Transfer for Spectrometry, and Related Systems and Methods

An atmospheric pressure interface 100 for a spectrometer 108 includes a wall 120 for separating an atmospheric pressure ionization chamber 112 from a reduced-pressure region 116 of the spectrometer. An ion inlet defining an ion path from the ionization chamber 112 to the reduced pressure region 116 is surrounded by a passage defining a gas path from the ionization chamber 112 to a gas outlet external to the reduced-pressure region 116. The passage for the gas may have a greater gas conductance than the ion inlet such that most of the gas passes into the gas passage and not the ion inlet. An interface device 124 is configured for applying a static electric field effective for focusing ions in the ionization chamber 112 preferentially into the ion inlet.