Laser spectroscopy

Laser spectroscopy studies matter by measuring how it absorbs, emits, or scatters laser light at characteristic frequencies. Narrow laser linewidths and tunable frequencies enable precise measurements of atomic and molecular structure.

Laser: A device that produces light by stimulated emission, typically concentrated in a narrow range of frequencies. Its coherence and narrow linewidth make precise frequency-resolved measurements possible.
Cavity ring-down spectroscopy: An absorption method that measures how quickly light decays inside an optical cavity. Long effective path lengths let lasers detect weakly absorbing trace gases.
Atomic spectroscopy: The study of light emitted or absorbed by atoms to determine their energy levels and composition. Atomic transitions are a central target of laser-frequency measurements.
Fourier-transform infrared spectroscopy: An infrared spectroscopy method that obtains a spectrum from an interferogram using Fourier transformation. It typically measures broad spectral ranges rather than scanning a narrow laser frequency.
Absorption spectroscopy: A method that identifies matter by measuring which frequencies it absorbs from incident light. Laser absorption reveals transitions when a tunable beam passes through a sample.
Laser-induced fluorescence: A technique that detects fluorescence from atoms or molecules excited by a laser. It supports highly sensitive measurements of species in flames, plasmas, and flowing gases.
Molecular spectroscopy: The study of molecular structure and dynamics through interactions with electromagnetic radiation. Laser spectroscopy extends molecular spectroscopy with controlled, narrowband excitation.
Dispersive spectroscopy: Spectroscopy that separates wavelengths with a prism or diffraction grating before detection. Its wavelength-resolved detection differs from measuring a laser's interaction at selected frequencies.
Fluorescence spectroscopy: A method that analyzes light emitted by a substance after it absorbs photons. Laser excitation can produce fluorescence whose frequency and intensity identify molecular states.
Saturated absorption spectroscopy: A nonlinear method that uses counterpropagating beams to resolve Doppler-free atomic absorption features. It provides narrow reference lines for stabilizing lasers to atomic transitions.

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