Absorption spectroscopy: Difference between revisions

Revision as of 21:14, 11 February 2025

Absorption spectroscopy

Absorption spectroscopy is a technique used in analytical chemistry to determine the presence and concentration of a substance in a sample by measuring the amount of light absorbed by the sample. This method is based on the principle that atoms and molecules absorb light at specific wavelengths, which correspond to the energy differences between their electronic states.

Principles of Absorption Spectroscopy

Absorption spectroscopy involves the interaction of light with matter. When light passes through a sample, certain wavelengths are absorbed by the sample's atoms or molecules. The amount of light absorbed at each wavelength is measured and used to create an absorption spectrum. This spectrum can be used to identify the substance and determine its concentration.

The basic components of an absorption spectrometer include a light source, a sample holder, a monochromator to select specific wavelengths of light, and a detector to measure the intensity of transmitted light.

Types of Absorption Spectroscopy

There are several types of absorption spectroscopy, each suited to different applications:

UV-Vis spectroscopy: Measures absorption in the ultraviolet and visible regions of the electromagnetic spectrum. It is commonly used for quantitative analysis of solutions.
IR spectroscopy: Measures absorption in the infrared region, providing information about molecular vibrations and structure.
Atomic absorption spectroscopy (AAS): Used to analyze metal ions in solutions by measuring the absorption of light by free atoms.

Applications

Absorption spectroscopy is widely used in various fields, including:

Environmental science: Monitoring pollutants in air and water.
Pharmaceutical industry: Quality control and drug development.
Astronomy: Identifying elements in stars and planets.

Astronomical Applications

In astronomy, absorption spectroscopy is used to study the composition of stars, planets, and other celestial bodies. By analyzing the absorption lines in the spectra of stars, astronomers can determine the elements present in their atmospheres.

Spectral Lines

Absorption lines, such as the Fraunhofer lines in the solar spectrum, are dark lines that appear in the spectrum when light is absorbed by atoms or molecules. These lines are characteristic of specific elements and can be used to identify them.

Gallery

Emission spectrum of iron, showing lines that correspond to absorption lines.
Identification of ices in the solar system using absorption spectroscopy.
Cumulative absorption spectrum from the Hubble Space Telescope.

Related Pages

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-{{Short description|Technique for measuring the absorption of radiation by a sample}}
+Absorption spectroscopy
-'''Absorption spectroscopy''' is a technique used in [[analytical chemistry]] to determine the presence and concentration of a substance in a sample by measuring the amount of light absorbed by the sample. This method is based on the principle that atoms and molecules absorb light at specific wavelengths, which correspond to the energy differences between their electronic, vibrational, or rotational states.
+[[File:Spectroscopy overview.svg|thumb|right|Overview of different types of spectroscopy, including absorption spectroscopy.]]
+'''Absorption spectroscopy''' is a technique used in [[analytical chemistry]] to determine the presence and concentration of a substance in a sample by measuring the amount of light absorbed by the sample. This method is based on the principle that atoms and molecules absorb light at specific wavelengths, which correspond to the energy differences between their electronic states.
 ==Principles of Absorption Spectroscopy==
-Absorption spectroscopy involves the interaction of light with matter. When light passes through a sample, certain wavelengths are absorbed by the sample, while others are transmitted. The amount of light absorbed at each wavelength is measured and used to create an [[absorption spectrum]]. This spectrum can provide information about the sample's composition and concentration.
+Absorption spectroscopy involves the interaction of light with matter. When light passes through a sample, certain wavelengths are absorbed by the sample's atoms or molecules. The amount of light absorbed at each wavelength is measured and used to create an [[absorption spectrum]]. This spectrum can be used to identify the substance and determine its concentration.
-The basic principle of absorption spectroscopy is described by [[Beer-Lambert law]], which relates the absorption of light to the properties of the material through which the light is traveling. The law is expressed as:
-: ''A = _lc''
-where ''A'' is the absorbance, ''_'' is the molar absorptivity, ''l'' is the path length of the sample, and ''c'' is the concentration of the absorbing species.
+The basic components of an absorption spectrometer include a light source, a sample holder, a monochromator to select specific wavelengths of light, and a detector to measure the intensity of transmitted light.
 ==Types of Absorption Spectroscopy==
-Absorption spectroscopy can be classified based on the type of radiation used and the nature of the transitions involved:
+There are several types of absorption spectroscopy, each suited to different applications:
-===Ultraviolet-Visible (UV-Vis) Spectroscopy===
+* '''[[Ultraviolet-visible spectroscopy|UV-Vis spectroscopy]]''': Measures absorption in the ultraviolet and visible regions of the electromagnetic spectrum. It is commonly used for quantitative analysis of solutions.
-[[UV-Vis spectroscopy]] involves the absorption of ultraviolet or visible light by molecules, leading to electronic transitions. It is widely used for quantitative analysis of solutions and for studying the electronic structure of molecules.
+* '''[[Infrared spectroscopy|IR spectroscopy]]''': Measures absorption in the infrared region, providing information about molecular vibrations and structure.
+* '''[[Atomic absorption spectroscopy|Atomic absorption spectroscopy (AAS)]]''': Used to analyze metal ions in solutions by measuring the absorption of light by free atoms.
-===Infrared (IR) Spectroscopy===
+==Applications==
-[[Infrared spectroscopy]] measures the absorption of infrared radiation by molecules, which causes vibrational transitions. It is commonly used to identify functional groups in organic compounds and to study molecular vibrations.
+Absorption spectroscopy is widely used in various fields, including:
-===Nuclear Magnetic Resonance (NMR) Spectroscopy===
+* [[Environmental science]]: Monitoring pollutants in air and water.
-[[NMR spectroscopy]] is based on the absorption of radiofrequency radiation by nuclei in a magnetic field. It provides detailed information about the structure, dynamics, and environment of molecules.
+* [[Pharmaceutical industry]]: Quality control and drug development.
+* [[Astronomy]]: Identifying elements in stars and planets.
-===Atomic Absorption Spectroscopy (AAS)===
+[[File:Sodium in atmosphere of exoplanet HD 209458.jpg|thumb|right|Detection of sodium in the atmosphere of exoplanet HD 209458 using absorption spectroscopy.]]
-[[Atomic absorption spectroscopy]] is used to determine the concentration of metal ions in solutions. It involves the absorption of light by free atoms in the gaseous state.
-==Applications==
+==Astronomical Applications==
-Absorption spectroscopy is used in various fields, including:
+In [[astronomy]], absorption spectroscopy is used to study the composition of [[stars]], [[planets]], and other celestial bodies. By analyzing the absorption lines in the spectra of stars, astronomers can determine the elements present in their atmospheres.
-* [[Environmental science]]: Monitoring pollutants and analyzing water quality.
+[[File:Fraunhofer lines.svg|thumb|right|Fraunhofer lines in the solar spectrum, an example of absorption lines.]]
-* [[Pharmaceutical industry]]: Determining the concentration of drugs and active ingredients.
-* [[Biochemistry]]: Studying proteins, nucleic acids, and other biomolecules.
-* [[Astronomy]]: Analyzing the composition of stars and planets by studying their absorption spectra.
-==Related pages==
+==Spectral Lines==
-* [[Spectroscopy]]
+Absorption lines, such as the [[Fraunhofer lines]] in the solar spectrum, are dark lines that appear in the spectrum when light is absorbed by atoms or molecules. These lines are characteristic of specific elements and can be used to identify them.
-* [[Emission spectroscopy]]
-* [[Fluorescence spectroscopy]]
-* [[Raman spectroscopy]]
 ==Gallery==
 <gallery>
-File:Spectroscopy overview.svg|Overview of different types of spectroscopy.
-File:Sodium in atmosphere of exoplanet HD 209458.jpg|Detection of sodium in the atmosphere of an exoplanet using absorption spectroscopy.
-File:Fraunhofer lines.svg|Fraunhofer lines in the solar spectrum, an example of absorption lines.
 File:Emission spectrum-Fe.svg|Emission spectrum of iron, showing lines that correspond to absorption lines.
-File:Identification of Ices in the Solar System.jpg|Use of absorption spectroscopy to identify ices in the solar system.
+File:Identification of Ices in the Solar System.jpg|Identification of ices in the solar system using absorption spectroscopy.
 File:Cumulative-absorption-spectrum-hubble-telescope.jpg|Cumulative absorption spectrum from the Hubble Space Telescope.
 </gallery>
+==Related Pages==
+* [[Spectroscopy]]
+* [[Emission spectroscopy]]
+* [[Fluorescence spectroscopy]]
+* [[Raman spectroscopy]]
 [[Category:Spectroscopy]]
+[[Category:Analytical chemistry]]
+[[Category:Astronomical spectroscopy]]