The difference between spectrophotometry and spectroscopy

The difference between spectrophotometry and spectroscopy

With the rapid growth of spectroscopy research, it’s important to make sure you know the difference between spectrophotometry and spectroscopy so you can make an informed decision when choosing your next spectroscopy instrument! Both of these terms are used interchangeably in daily practice, but do they actually mean the same thing?

The answer is yes…and no. Let’s look at the difference between spectrophotometry and spectroscopy, and then go over three key factors that you should consider when purchasing your next ultraviolet-visible (UV-Vis) instrumentation!

What Is Spectrophotometry?

Spectrophotometry (from Greek spectrum Σπείρω meaning I examine, and φῶς meaning light) is an analytical technique that measures how much light passes through a specific sample. It is usually performed using a spectrophotometer, which contains a monochromator, that breaks up light into its component wavelengths.

Light source: The most common light source used in spectrophotometry is a deuterium lamp, although other lamp types can be used with appropriately calibrated instruments such as Nernst lamps or xenon arc lamps. Sometimes samples are illuminated with full sunlight passed through diffusers.

How Do I Use Spectrophotometers?

Although they’re both quite similar, there are some key differences to note between spectrophotometry and spectroscopy. Spectrophotometers are used to measure an absorbance or transmittance of light at different wavelengths through a sample or solution.

You can use a spectrometer to study chemical compounds, determine molecular weight of organic chemicals, estimate water content in soil or make sure your beer is at its prime for consumption. Spectroscopists on the other hand study absorption, emission and scattering of radiation from atoms/molecules in order to obtain information about composition, structure and behavior (of atoms/molecules). Other examples include determining masses of atoms via their radiative properties as well as studying electromagnetic radiation produced by distant stars. The take-away here?

What Is spectroscopy?

Spectroscopy, which means to study (something) by light, is a laboratory technique that allows scientists to obtain a chemical fingerprint of a substance. It does so by looking at its unique wavelengths or frequencies of light. This information helps identify what a particular substance is made up of. Spectroscopy has many applications in both science and medicine.

In addition to identifying substances, it’s also used to measure physical properties like mass and concentration, to detect elements or compounds, to determine atomic structures, or even just to create pretty pictures! There are many different kinds of spectrometers which use light in different ways.

How Do I Use spectroscopy?

In a laboratory setting, spectroscopy is used to break down an object or substance into its individual parts. Spectrometers isolate individual elements through light wavelengths, providing an accurate depiction of an object’s chemical makeup.

These machines are used in research labs as well as industries that depend on detecting specific materials within a given product. For example, oil companies use spectrometers to test pollutants within certain samples of crude oil; they also use these machines to screen groundwater for chemicals that may be present in nearby fracking sites.

Difference between spectrophotometry and spectroscopy

Measurement techniques are a vital part of laboratory analysis, but they come in many forms. Here, we take a look at some commonly used methods: absorption (spectrophotometry), fluorescence emission (fluorimetry), fluorescence excitation (fluorimetry), scattering/transmission (absorbance or transmittance) and luminescence emission.

the difference between spectrophotometry and spectroscopy is

1. Spectrophotometers are used to measure absorbance of light in a sample, while spectroscopy are used to measure absorption (absorbance) of radiation by matter.

2.Spectrophotometers are instruments that use monochromatic light sources such as lasers or LEDs to obtain a spectrum from which they can derive an absorbance spectrum from their measurements at different wavelengths. 3.Spectroscopy is used to measure absorption of radiation by matter, while spectrophotometry is used to measure absorption of light by matter (or vice versa).

4. Spectrophotometer measures transmittance of radiation by matter, while spectroscopy measures transmission of radiation through matter (or vice versa).

5. Spectrophotometer measures reflectance of radiation by matter, while spectroscopy measures reflectivity of matter (or vice versa).

6.Spectrophotometers measure fluorescence emitted from a sample at different wavelengths, while spectroscopy is used to measure fluorescence emission of light from a sample (or vice versa).

7.Spectrophotometers measure luminescence emitted from a sample at different wavelengths, while spectroscopy is used to measure luminescence emission of light from a sample (or vice versa).

Final Thoughts

Spectroscopy is an analytical technique used to measure physical properties such as mass, volume, density, etc. It can be used for applications in a variety of fields including geology and analytical chemistry.

Spectrophotometry refers to a specialized type of spectroscopy which can be used to determine optical absorption, emission or scattering properties based on transmitted radiation over a range of wavelengths. The key difference between spectroscopy and spectrophotometry is that while both are types of spectroscopy, only spectrophotometry deals with measurements related to light.


Spectrophotometry and spectroscopy are both ways to measure light. The key difference is in their intended use. Spectrometers are generally used to measure wavelengths in order to determine chemical composition or concentration of some sample, while spectrographs measure intensity of light over a specific wavelength in order to distinguish different objects by their unique spectral signature.

In most cases, a chemists use a very expensive machine called an ultraviolet-visible (UV-Vis) Spectrometer while astronomers use relatively cheap machines called spectrographs.

Leave a Reply

Your email address will not be published.