Any of various instruments used to analyze the component parts of a sample by separating its parts into a spectrum.♦ In a light spectroscope, light is focused into a thin beam of parallel rays by a lens, and then passed through a prism or diffraction grating that separates the light into a frequency spectrum. The intensity of light at different frequencies in the spectrum can be analyzed to determine certain properties of the source of the light, such as its chemical composition or how quickly it is moving.♦ In a mass spectroscope, sample ions are beamed through an electric or magnetic field that deflects the ions; the amount of deflection depends on the ratio of their mass to their electric charge. The ion beam is thus split into separate bands; the collection of bands is called the mass spectrum of the sample, and can be analyzed to determine the distribution of ions in the sample. Spectroscopes are also called spectrographs.

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