In chemistry, spectrophotometry is the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength.wikipedia
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DU spectrophotometer

Beckman DU SpectrophotometerBeckman DU ultraviolet spectrophotometerDU line
The last and most popular model became Model D which is better recognized now as the DU spectrophotometer which contained the instrument case, hydrogen lamp with ultraviolent continuum and a better monochromator.
This model of spectrophotometer enabled scientists to easily examine and identify a given substance based on its absorption spectrum, the pattern of light absorbed at different wavelengths.

Beckman Coulter

Beckman InstrumentsBeckmanBeckman Instrument Company
Invented by Arnold O. Beckman in 1940, the spectrophotometer was created with the aid of his colleagues at his company National Technical Laboratories founded in 1935 which would become Beckman Instrument Company and ultimately Beckman Coulter.
In the 1940s, Beckman changed the name to Arnold O. Beckman, Inc. to sell oxygen analyzers, the Helipot precision potentiometer, and spectrophotometers.

Time-resolved spectroscopy

Time-resolved fluorescence spectroscopytime-resolvedTime-resolved fluorometry (TRF)
It is more specific than the general term electromagnetic spectroscopy in that spectrophotometry deals with visible light, near-ultraviolet, and near-infrared, but does not cover time-resolved spectroscopic techniques.
If the process under study is slow, then the time resolution can be obtained with a continuous (i.e., not pulsed) probe beam and repeated conventional spectrophotometric techniques.

Astronomical spectroscopy

In astronomy, the term spectrophotometry refers to the measurement of the spectrum of a celestial object in which the flux scale of the spectrum is calibrated as a function of wavelength, usually by comparison with an observation of a spectrophotometric standard star, and corrected for the absorption of light by the Earth's atmosphere.
The flux scale of a spectrum can be calibrated as a function of wavelength by comparison with an observation of a standard star with corrections for atmospheric absorption of light; this is known as spectrophotometry.


photocellAmbient lightAmbient light sensor
Then the photon flux density (watts per metre squared usually) of the transmitted or reflected light is measured with a photodiode, charge coupled device or other light sensor.
A 1-D array of photodetectors, as in a spectrophotometer or a Line scanner, may be used to measure the distribution of light along a line.


colorimetriccolor measurementchromatics
Visible region 400–700 nm spectrophotometry is used extensively in colorimetry science.
It is similar to spectrophotometry, but is distinguished by its interest in reducing spectra to the physical correlates of color perception, most often the CIE 1931 XYZ color space tristimulus values and related quantities.

Fourier-transform infrared spectroscopy

FTIRFourier transform infraredFourier Transform Infrared Spectrometer
This technique is called Fourier transform infrared spectroscopy.
The first low-cost spectrophotometer capable of recording an infrared spectrum was the Perkin-Elmer Infracord produced in 1957.


Samples are usually prepared in cuvettes; depending on the region of interest, they may be constructed of glass, plastic (visible spectrum region of interest), or quartz (Far UV spectrum region of interest).
This measurement is done with a spectrophotometer.


Spectrophotometry uses photometers, known as spectrophotometers, that can measure a light beam's intensity as a function of its color (wavelength).
The principle of spectrophotometers and filter photometers is that (as far as possible) monochromatic light is allowed to pass through a container (cell) with optically flat windows containing the solution.


spectroscopiclaser spectroscopyspectroscopist
It is more specific than the general term electromagnetic spectroscopy in that spectrophotometry deals with visible light, near-ultraviolet, and near-infrared, but does not cover time-resolved spectroscopic techniques.
Spectral measurement devices are referred to as spectrometers, spectrophotometers, spectrographs or spectral analyzers.


Czerny-Turneroptical spectrophotometersCzerny Turner
Historically, spectrophotometers use a monochromator containing a diffraction grating to produce the analytical spectrum.
A spectrophotometer built with a high quality double monochromator can produce light of sufficient purity and intensity that the instrument can measure a narrow band of optical attenuation of about one million fold (6 AU, Absorbance Units).

Beer–Lambert law

Beer-Lambert LawBeer's lawanalysis of mixtures
If the compound is more concentrated more light will be absorbed by the sample; within small ranges, the Beer-Lambert law holds and the absorbance between samples vary with concentration linearly.
Beer–Lambert law can be applied to the analysis of a mixture by spectrophotometry, without the need for extensive pre-processing of the sample.


photomultiplier tubephotomultiplier tubesPMT
If a single detector, such as a photomultiplier tube or photodiode is used, the grating can be scanned stepwise (scanning spectrophotometer) so that the detector can measure the light intensity at each wavelength (which will correspond to each "step").
can be used for transmission-mode; favorable response to a NaI:Tl scintillator flashes makes them widely used in gamma spectroscopy and radiation detection; high-temperature bialkali (Na-K-Sb), can operate up to 175 °C, used in well logging, low dark current at room temperature; multialkali (Na-K-Sb-Cs), (also called S20), wide spectral response from ultraviolet to near-infrared, special cathode processing can extend range to 930 nm, used in broadband spectrophotometers; solar-blind (Cs-Te, Cs-I), sensitive to vacuum-UV and ultraviolet, insensitive to visible light and infrared (Cs-Te has cutoff at 320 nm, Cs-I at 200 nm).


Spectroradiometers, which operate almost like the visible region spectrophotometers, are designed to measure the spectral density of illuminants.

Ultraviolet–visible spectroscopy

λ max ultraviolet-visible spectroscopyλ max
Additionally, some specialized instruments, such as spectrophotometers built onto microscopes or telescopes, are single-beam instruments due to practicality.

Spectronic 20

The Spectronic 20 is a brand of single-beam spectrophotometer, designed to operate in the visible spectrum across a wavelength range of 340 nm to 950 nm, with a spectral bandpass of 20 nm.

Cytochrome P450

cytochrome P-450cytochrome P450 oxidaseCYP
The term "P450" is derived from the spectrophotometric peak at the wavelength of the absorption maximum of the enzyme (450 nm) when it is in the reduced state and complexed with carbon monoxide.

Cary 14 Spectrophotometer

Cary 14 UV-Vis-NIR
The Cary Model 14 UV-VIS Spectrophotometer was a double beam recording spectrophotometer designed to operate over the wide spectral range of ultraviolet, visible and near infrared wavelengths (UV/Vis/NIR).

Robert Brattain

He is recognized as one of America’s leading infrared spectroscopists for his work in designing several models of spectrophotometer, and for using the infrared spectrophotometer to determine the β-lactam structure of penicillin.

Bromopyrogallol red

Bromopyrogallol red is frequently used in analytical chemistry as a reagent for spectrophometric analysis and as an complexometric indicator.

Gaia (spacecraft)

GaiaGaia spacecraftGaia'' spacecraft
The spectrophotometric measurements will provide the detailed physical properties of all stars observed, characterizing their luminosity, effective temperature, gravity and elemental composition.


Its presence can be determined by either by spectrophotometry (measuring the absorption of particular wavelengths of light) or simple visual examination.

Matthew Pothen Thekaekara

Rev. Dr. Matthew Pothen Thekaekara (1914–1974) was a scientist and author of many books and papers relating to spectrophotometry and the solar constant besides works on theology.

Flow injection analysis

Flow injection
Over past 30 years, FIA techniques developed into a wide array of applications using spectrophotometry, fluorescence spectroscopy, atomic absorption spectroscopy, mass spectrometry, and other methods of instrumental analysis for detection.

Compton edge

Compton profile spectroscopy
In spectrophotometry, the Compton edge is a feature of the spectrograph that results from the Compton scattering in the scintillator or detector.