View source for Spectrometer

{{Short description|Used to measure spectral components of light}}
{{For|the field of study|Spectroscopy}}

{{More citations needed|date=November 2023}}
[[File:Silver Target in XPS Spectrometer.jpg|thumb|An [[X-ray photoelectron spectroscopy|XPS]] spectrometer]]

A '''spectrometer''' ({{IPAc-en|s|p|ɛ|k|ˈ|t|r|ɒ|m|ɪ|t|ər}}) is a scientific instrument used to separate and measure [[Spectrum|spectral]] components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where the spectral components are somehow mixed. In [[visible light]] a spectrometer can separate white [[light]] and measure individual narrow bands of color, called a spectrum. A [[mass spectrometer]] measures the spectrum of the masses of the atoms or molecules present in a gas. The first spectrometers were used to split light into an array of separate colors. Spectrometers were [[History_of_spectroscopy|developed]] in early studies of [[physics]], [[astronomy]], and [[chemistry]]. The capability of [[spectroscopy]] to determine [[Analytical_chemistry#Spectroscopy|chemical composition]] drove its advancement and continues to be one of its primary uses. Spectrometers are used in [[Astronomical spectroscopy|astronomy]] to analyze the chemical composition of [[Astronomical_spectroscopy#Stars_and_their_properties|stars]] and [[Astronomical_spectroscopy#Planets.2C_asteroids.2C_and_comets|planets]], and spectrometers gather data on the [[Big_Bang#Cosmic_microwave_background_radiation|origin of the universe]]. 

Examples of spectrometers are devices that separate [[Subatomic_particles|particles]], [[atoms]], and [[molecules]] by their [[mass]], [[momentum]], or [[energy]]. These types of spectrometers are used in [[Analytical_chemistry#Mass_spectrometry|chemical analysis]] and [[particle physics]].<ref>{{Cite web |title=Web of Science |url=https://www.webofscience.com/wos/woscc/full-record/WOS:000779781700009?UT=000779781700009 |access-date=2024-11-17 |website=www.webofscience.com}}</ref>

==Types of spectrometer==
===Optical spectrometers or optical emission spectrometer===
{{main|Optical spectrometer}}
[[File:Deuterium lamp 1.png|240px|right|thumb|Spectrum of light emitted by a [[deuterium]] lamp in the UV, visible and near infrared part of the electromagnetic spectrum.]]
====Optical absorption spectrometers====
[[Optical spectrometer]]s (often simply called "spectrometers"), in particular, show the intensity of [[light]] as a function of wavelength or of frequency. The different wavelengths of light are separated by [[refraction]] in a [[Prism (optics)|prism]] or by [[diffraction]] by a [[diffraction grating]]. [[Ultraviolet–visible spectroscopy]] is an example.

These spectrometers utilize the phenomenon of [[Dispersion (optics)|optical dispersion]]. The light from a source can consist of a [[continuous spectrum]], an [[emission spectrum]] (bright lines), or an [[absorption spectrum]] (dark lines). Because each element leaves its [[spectral signature]] in the pattern of lines observed, a [[Spectroscopy|spectral analysis]] can reveal the composition of the object being analyzed.<ref name="openstax-astro">{{Open Access}} OpenStax, Astronomy. OpenStax. 13 October 2016. <http://cnx.org/content/col11992/latest/></ref>

A spectrometer that is calibrated for measurement of the incident optical power is called a [[spectroradiometer]]. <ref>{{cite book |last1=Schneider |first1=T. |last2=Young |first2=R. |last3=Bergen |first3=T. |last4=Dam-Hansen |first4=C |last5=Goodman |first5=T. |last6=Jordan |first6=W. |last7=Lee |first7=D.-H |last8=Okura |first8=T. |last9=Sperfeld |first9=P. |last10=Thorseth |first10=A |last11=Zong |first11=Y. |title=CIE 250:2022 Spectroradiometric Measurement of Optical Radiation Sources |date=2022 |publisher=CIE - International Commission on Illumination |location=Vienna |isbn=978-3-902842-23-7 |url=https://orbit.dtu.dk/en/publications/cie-2502022-spectroradiometric-measurement-of-optical-radiation-s}}</ref>

====Optical emission spectrometers====
[[Atomic emission spectroscopy|Optical emission spectrometer]]s (often called "OES or spark discharge spectrometers"), are used to evaluate [[metals]] to determine the chemical composition with very high accuracy. A spark is applied through a high voltage on the surface which vaporizes particles into a plasma. The particles and ions then emit radiation that is measured by detectors (photomultiplier tubes) at different characteristic wavelengths.<ref>{{cite journal |last1=Yang |first1=Jiahui |last2=Luo |first2=Yijing |last3=Su |first3=Yubin |last4=Li |first4=Yuanyuan |last5=Lin |first5=Yao |last6=Zheng |first6=Chengbin |title=Direct coupling of liquid–liquid extraction with 3D-printed microplasma optical emission spectrometer for speciation analysis of mercury in fish oil |journal=Microchemical Journal |date=August 2022 |volume=179 |pages=107569 |doi=10.1016/j.microc.2022.107569 }}</ref>

===Electron spectroscopy===
{{main|Electron spectroscopy}}
Some forms of spectroscopy involve analysis of electron energy rather than photon energy. [[X-ray photoelectron spectroscopy]] is an example.<ref>{{cite book |doi=10.1016/B978-075067509-3/50007-5 |chapter=X-ray analysis of metallic materials |title=Smithells Metals Reference Book |date=2004 |isbn=978-0-7506-7509-3 |editor1-first=W.F. |editor1-last=Gale |editor2-first=T.C. |editor2-last=Totemeier }}</ref>

===Mass spectrometer===
{{main|Mass spectrometry}}
A [[mass spectrometer]] is an analytical instrument that is used to identify the amount and type of chemicals present in a sample by measuring the [[mass-to-charge ratio]] and abundance of gas-phase [[ion]]s.<ref>{{GoldBookRef|title=Mass spectrometer|file=M03732}}</ref>

====Time-of-flight spectrometer====
The energy spectrum of particles of known mass can also be measured by determining the time of flight between two [[detector]]s (and hence, the velocity) in a [[time-of-flight spectrometer]]. Alternatively, if the particle-energy is known, masses can be determined in a [[time-of-flight mass spectrometer]].

====Magnetic spectrometer====
[[File:FuerzaCentripetaLorentzP.svg|thumb|A positive charged particle moving in a circle under the influence of the Lorentz force '''F''']]
When a fast [[charged particle]] (charge ''q'', mass ''m'') enters a constant magnetic field ''B'' at right angles, it is deflected into a circular path of radius ''r'', due to the [[Lorentz force]]. The momentum ''p'' of the particle is then given by

: <math>p = mv = qBr</math>,
[[File:Focus01.png|thumb|left|Focus of a magnetic semicircular spectrometer]]where ''m'' and ''v'' are mass and velocity of the particle.<ref>{{cite journal |last1=Aguilar |first1=M. |last2=Ali Cavasonza |first2=L. |last3=Ambrosi |first3=G. |last4=Arruda |first4=L. |last5=Attig |first5=N. |last6=Barao |first6=F. |last7=Barrin |first7=L. |last8=Bartoloni |first8=A. |last9=Başeğmez-du Pree |first9=S. |last10=Bates |first10=J. |last11=Battiston |first11=R. |last12=Behlmann |first12=M. |last13=Beischer |first13=B. |last14=Berdugo |first14=J. |last15=Bertucci |first15=B. |last16=Bindi |first16=V. |last17=de Boer |first17=W. |last18=Bollweg |first18=K. |last19=Borgia |first19=B. |last20=Boschini |first20=M.J. |last21=Bourquin |first21=M. |last22=Bueno |first22=E.F. |last23=Burger |first23=J. |last24=Burger |first24=W.J. |last25=Burmeister |first25=S. |last26=Cai |first26=X.D. |last27=Capell |first27=M. |last28=Casaus |first28=J. |last29=Castellini |first29=G. |last30=Cervelli |first30=F. 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|hdl=10281/287394 |hdl-access=free }}</ref> The focusing principle of the oldest and simplest magnetic spectrometer, the semicircular spectrometer,<ref>{{cite journal |last1=Danysz |first1=J. |title=Sur les rayons β de la famille du radium |journal=Le Radium |date=1912 |volume=9 |issue=1 |pages=1–5 |doi=10.1051/radium:01912009010100 }}</ref><ref>{{cite journal |last1=Danysz |first1=Jean |title=Sur les rayons β des radiums B, C, D, E |journal=Le Radium |date=1913 |volume=10 |issue=1 |pages=4–6 |doi=10.1051/radium:019130010010401 }}</ref> invented by J. K. Danisz, is shown on the left. A constant magnetic field is perpendicular to the page. Charged particles of momentum ''p'' that pass the slit are deflected into circular paths of radius ''r = p/qB''. It turns out that they all hit the horizontal line at nearly the same place, the focus; here a particle counter should be placed. Varying ''B'', this makes possible to measure the energy spectrum of [[alpha particle]]s in an alpha particle spectrometer, of [[beta particle]]s in a beta particle spectrometer,<ref name="Siegbahn">{{cite book |last1=Siegbahn |first1=Kai |title=Alpha- Beta- and Gamma-ray Spectroscopy |date=1965 |publisher=North-Holland Publishing Company |isbn=978-0-444-10695-7 }}{{pn|date=November 2024}}</ref> of particles (e.g., fast [[ions]]) in a particle spectrometer, or to measure the relative content of the various masses in a [[mass spectrometer]].

Since Danysz' time, many types of magnetic spectrometers more complicated than the semicircular type have been devised.<ref name="Siegbahn" />

==Resolution==
Generally, the [[spectral resolution|resolution]] of an instrument tells us how well two close-lying energies (or wavelengths, or frequencies, or masses) can be resolved. Generally, for an instrument with mechanical slits, higher resolution will mean lower intensity.<ref>{{Cite web |title=Web of Science |url=https://www.webofscience.com/wos/woscc/full-record/WOS:000749782900001?UT=000749782900001 |access-date=2024-11-17 |website=www.webofscience.com}}</ref>

==See also==
* [[Optical spectrometer]]
* [[Imaging spectrometer]]
* [[Spectroradiometer]]

== References ==
{{Reflist}}

{{commons category|Spectrometers}}

{{BranchesofSpectroscopy}}
{{mass spectrometry}}

{{Authority control}}

[[Category:Spectrometers| ]]