mass spectrometry (mass spectroscopy)

(of elements) A method for experimentally determining isotopic masses and isotopic abundances . A sample of an element is converted into a stream of ions and passed through an electromagnetic field. Ions with different charge-to-mass ratios are deflected by different amounts, and strike different spots on a film plate or other detector. From the position of the spots, the mass of the ions can be determined; from the intensity of the spot, the relative number of ions (the isotopic abundance) can be determined.