Thermal Ionization Mass Spectrometer (TIMS)

Definition

A thermal ionization mass spectrometer (TIMS) consists of (1) an ion source (here a solid source), (2) a magnet (analyzer) that splits the ions depending on their mass to charge ratio (momentum filter), and (3) one or multiple collectors that measure the magnitude of the ion beams such that isotopic ratios of a given element can be computed (Nier-type spectrometer, Nier, 1940).

Prior to analysis, a solution containing the purified sample is loaded on a metal filament (Re, Ta, Pl, or W) and dried down. In the evacuated source, ions are generated using the process of surface ionization by thermally heating the filament to ca. 1,200–1,800 ºC. In a single-filament configuration, ions are directly emitted from the loaded sample; in a double- or triple-filament configuration, the sample is loaded on one or both of the side filaments where volatilization takes place followed by ionization using the center filament that is heated to a significantly higher temperature. Depending on...