Patent ID: 7791042

Claim:
An apparatus comprising an ion source that includes: structure having separate first and second ion volumes therein; an electron source structure having first and second portions with each of the first and second portions additionally configured with electron gates that selectively supply electrons to the first and second ion volumes, respectively, the electron source structure having a first operational mode in which the second portion substantially prevents a supply of electrons to the second ion volume and in which electrons are supplied to the first ion volume under control of the first portion, and having a second operational mode in which the first portion substantially prevents a supply of electrons to the first ion volume and in which electrons are supplied to the second ion volume under control of the second portion; and wherein the structure with the ion volumes includes a passage that provides communication between the first and second ion volumes, sample supply structure that facilitates a supply to the first ion volume of particles of a sample material, and gas supply structure that facilitates a supply of a reagent gas to the first ion volume; wherein ionization that occurs within the first ion volume is chemical ionization; and wherein ionization that occurs within the second ion volume is electron ionization; and wherein the sample supply structure includes a gas chromatography column supported for movement between first and second positions in which the column emits the particles of the sample material in the first ion volume and in the second ion volume, respectively.