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At its simplest, a Raman spectroscope shoots a single-wavelength laser at a sample. The sample¹s molecules absorb, emit or scatter incoming photons. A filter captures scattered photons with the same wavelength as the laser, allowing the photons with different wavelengths to pass through. These collide with a grating that, like a prism, separates them by wavelength. The resulting pattern, or spectral fingerprint, is passed to a computer where the sample¹s chemical makeup is determined.
Credit: J. Korenblat (source: Materials Science and Metallurgy DEPT., Univ. of Cambridge); istock/homebredcorgi