Emission spectrum

Emission spectrum refers to the spectrum of frequencies of electromagnetic radiation emitted due to an atom or molecule making a transition from a high energy state to a lower energy state. The energy of the emitted photon is equal to the energy difference between the two states. There are many possible electron transitions for each atom, and each transition has a specific energy difference. This collection of different transitions, leading to different radiated wavelengths, make up an emission spectrum. Each element's emission spectrum is unique. Therefore, spectroscopy can be used to identify the elements in matter of unknown composition.

Overview

An emission spectrum is the range or array of wavelengths (spectra) obtained when the light emitted by a substance is passed through a prism or other dispersing device. This spectrum is characteristic of the emitting substance and the type of excitation to which it is subjected.

Types of Emission Spectra

There are two types of emission spectra: continuous spectra and line spectra.

Continuous Spectrum

A continuous spectrum usually has the colors of a rainbow. It is a complete spectrum of light which contains all the colors or wavelengths with no gaps.

Line Spectrum

A line spectrum is an emission spectrum consisting of separate isolated lines. Each line corresponds to a specific wavelength or frequency. The lines are the result of the atom releasing energy in the form of light when the electrons fall to a lower energy level.

Applications

Emission spectra are used in various scientific fields. They are used in astronomy to study the elements present in stars and galaxies. They are also used in chemistry and physics to identify and study elements and compounds.

See Also

• Absorption spectrum
• Spectroscopy
• Atomic spectral line
• Hydrogen spectral series

References

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  Emission_spectrum

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  Sodium emission lines at Cambridge Science Festival 2016

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  Hydrogen emission spectrum

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  Iron emission spectrum

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  Atomic line spectrum