How do mass spectrometers measure parent and daughter isotopes in radiometric dating?

Mass spectrometers measure parent and daughter isotopes by sorting gaseous ions based on their mass-to-charge ratios. In a typical analysis, a sample is vaporized to produce a beam of charged atoms, which is then passed through a magnetic field in a vacuum. This field separates the beam into components based on mass, allowing the instrument to measure the relative abundance of specific isotopes.12

To determine the absolute number of atoms, researchers often use isotope dilution. By adding a known amount of an artificially enriched isotope, or "spike," to the sample before dissolution, scientists can calculate the concentration of natural parent and daughter isotopes by measuring the ratio of the natural isotopes to the spike.23

Modern techniques include:
* Thermal Ionization Mass Spectrometry: Used for high-precision isotopic abundances.3
* Accelerator Mass Spectrometry: Counts individual atoms directly, significantly increasing sensitivity for isotopes like carbon-14.3
* In-situ Analysis: Instruments like the sensitive high-resolution ion microprobe (SHRIMP) and LA-ICP-MS use focused beams to analyze mineral surfaces without chemical dissolution.3