Photonics Dictionary


Spectroscopy is a technique used in the study of interactions between matter and electromagnetic radiation. It involves measuring and analyzing how different materials absorb, emit, or scatter light, often as a function of wavelength or frequency. This analysis provides valuable information about the composition, structure, and properties of the substances being studied.

The basic principle behind spectroscopy is that different substances interact with light in unique ways, resulting in characteristic patterns in the emitted, transmitted, or reflected light. The spectrum obtained from a spectroscopic analysis is a plot of the intensity of light as a function of its wavelength or frequency.

There are various types of spectroscopy, including:

Absorption spectroscopy: This technique involves measuring the absorption of light by a substance as it passes through or interacts with the material. Absorption spectra are often used to identify the presence of specific compounds and determine their concentrations.

Emission spectroscopy: In emission spectroscopy, the focus is on the light emitted by a substance after it has absorbed energy. This type of spectroscopy is used to study the energy levels of atoms and molecules and is often applied in the field of atomic and molecular physics.

Fluorescence and phosphorescence spectroscopy: These techniques involve the emission of light by a substance after it has absorbed light energy. Fluorescence occurs rapidly, while phosphorescence involves a delayed emission.

Infrared spectroscopy: This technique analyzes the infrared region of the electromagnetic spectrum. It is particularly useful for studying molecular vibrations and identifying functional groups in organic compounds.

Nuclear magnetic resonance (NMR) spectroscopy: NMR spectroscopy is based on the interaction of atomic nuclei with strong magnetic fields and radiofrequency radiation. It is widely used for elucidating the structure of organic compounds.

Mass spectrometry: While not a traditional form of spectroscopy, mass spectrometry is often used in conjunction with spectroscopic techniques. It measures the mass-to-charge ratio of ions and is valuable for identifying and quantifying compounds.

Spectroscopy plays a crucial role in various scientific disciplines, including chemistry, physics, astronomy, environmental science, and biochemistry. It enables researchers to gain insights into the composition and properties of matter at a molecular and atomic level.

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