Spectroscopy is regarded as a theoretical science, while spectrometry is considered a practical measurement. Both are differently related to the interactions between matter and light.
In this article, spectroscopy and spectrometry are defined, and their differences are explained briefly but comprehensively. In addition to that, we have also tried to differentiate between spectroscopy and spectrophotometry.
So let us wait no more and find out what is the difference between spectroscopy and spectrometry.
What is spectroscopy?
Spectroscopy is described as the study of the interaction of matter with electromagnetic radiation as a function of wavelength or frequency. It investigates and measures the spectra resulting from this interaction for compound determination and identification purposes.
Electromagnetic radiations of a particular wavelength range pass through the sample that contains the analyte of interest. As a result of this interaction, a particular wavelength or frequency of radiant light gets absorbed or emitted by the sample.
Therefore, spectroscopy can be classified into the following two types:
- Absorption spectroscopy: This is a spectroscopic technique that operates by measuring the wavelength of light absorbed as a result of the interaction between matter and energy.
- Emission spectroscopy: This spectroscopic technique functions by examining the wavelength of photons or molecules. Energy or light emission occurs during the transition of atoms or molecules from an excited state to the ground state.
What is spectrometry?
Spectrometry is regarded as the application of spectroscopy used to deal with the quantitative measurement of a particular spectrum. This application is used for the analysis and interpretation of spectroscopy.
Types of spectrometers
Spectrometers are available in different designs to select according to specific measurements, for instance:
Optical spectrometers
- Optical spectrometer is very common in research areas.
- This type measures light intensity by detecting optical absorption or emission.
Mass Spectrometers
- Mass spectrometer determines the analyte’s identity in a sample by measuring the mass-to-charge ratio.
- This type of spectrophotometer is often used in forensic analysis. It facilitates investigators in gaining clues from trace evidence.
Nuclear magnetic resonance (NMR) spectrometers
- The NMR spectrometer utilizes the magnetic field required to magnetize the nuclei of targeted atoms.
- It works by measuring the magnetic resonance frequencies of magnetized nuclei, which are then depicted on the spectrum.
Electron spectrometers
- Unlike other spectrometers, electron spectrometers are not commonly used.
- These are used to measure the energy possessed by a beam of electrons. It separates electrons according to their energy levels by bending the beam under the influence of an electric or magnetic field.
What is the difference between spectroscopy and spectrometry?
The terms spectroscopy and spectrometry are usually used interchangeably, but there exist some differences that are pointed out below.
| Spectroscopy | Spectrometry |
| As described earlier, spectroscopy studies the interaction between matter and radiant energy. | Spectrometry is regarded as the application of spectroscopy. It measures the interactions between matter and electromagnetic radiation. Spectrometry deals with the bombardment of the high-energy electric beams over the sample resulting in the fragmentation of ions. |
| Ultraviolet and infrared spectroscopy are among the few examples of spectroscopy. | Mass spectrometry is a common example of spectrometry. |
| Electromagnetic radiations such as ultraviolet and infrared are used. | Electromagnetic radiations are not directly used in this technique. |
| Spectroscopy is a theoretical part of science. This technique is not capable of generating results on its own. |
Spectrometry is a practical approach that produces quantifiable results. These results are then can be analyzed. |
| Spectroscopy is considered a non-destructive technique. This means that it does not alter the composition of the sample. | Spectrometry is known to be a destructive technique which means it invariably alters the sample composition. |
What is the difference between spectroscopy and spectrophotometry?
Both spectroscopy and spectrophotometry are similar terms yet not interchangeable. While approaching related concepts, they deal with different scientific interactions and outcomes to obtain insights.
Some prominent differences between these two are mentioned below.
| Spectroscopy | Spectrophotometry |
| Spectroscopy studies the interaction between matter and energy. -Once matter absorbs light, its atoms achieve an excited state. -This produces an observable interaction via visible light produced by electromagnetic waves on the spectrum. |
Spectrophotometry works based on the principle that every chemical compound can absorb, transmit or reflect light. – This technique can determine the amount of light absorbed by the sample. – This is done by measuring the intensity of the light when its beam passes from the sample. |
| Spectroscopy employs a spectrometer responsible for measuring physical variations in the spectrum. Depending upon the amount of ultraviolet, visible and infrared light projected by a material, a spectrometer also collects information. |
This technique requires a spectrophotometer, a device that quantitatively measures the transmission or reflectance of a sample material as a function of wavelength. |
| Cannot produce results alone. | Can produce results on its own. |
| Spectroscopy is applicable in the fields of chemistry, physics and astronomy. | Spectrophotometry finds its application in the field of biochemistry and biology in addition to chemistry and physics. |
Why do you need mass spectrometry to analyze and interpret spectroscopy?
Mass spectroscopy is needed to interpret and analyze spectroscopic results because it is a way of chemical analysis.
Mass spectroscopy is the approach that performs analysis by measuring the mass-to-charge (m/z) ratio of the components present in a sample.
Mass spectrometry is applied:
- To distinguish among different isotopes of the same element.
- To measure the exact molecular weight of components of a sample.
- For the identification of unknown compounds in a sample.
Prominent features of mass spectrometry
Despite various types of spectrometers, they all contain three common features,
Ionization:
- First and foremost is the source of ionization that can ionize the atoms or molecules present in the sample.
- Ionization is necessary as neutral species are not steered by the electric field applied in mass spectrometers.
Mass Analyzer:
The second important feature is the mass analyzer itself. Based on how the mass analyzer measures the m/z ratio, different variants are available such as,
- Magnetic sector analyzer
- Time of flight (ToF) analyzer
- Quadrupole mass analyzer
Detector:
The third main feature of a mass spectrometer is a detector used for the detection of ions with specific m/z ratios.
Detectors, too, are of various types, among which faraday cups, electron multipliers, channel plates and channeltrons are the most common.
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