--subdivision Spectra under individual chemicals and groups of chemicals, individual materials and types of materials, elementary particles, and celestial bodies, e.g. Copper--Spectra; Metals--Spectra; Protons--Spectra; Stars--Spectra
The measurement of the amplitude of the components of a complex waveform throughout the frequency range of the waveform. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
