A Thermal Ionization Mass Spectrometer (TIMS) is an instrument that measures isotopic ratios after electrical excitation of a sample causes ionization of the isotopes.
Boron isotope ratios were measured on a Thermo TRITON multicollector thermal ionization mass spectrometer at LDEO in negative-ion mode (NTIMS, see detailed methodology in Foster et al., 2013)
TI Mass Spec - Thermo TRITON multicollector thermal ionization mass spectrometer