What is a Spectrometer?

What is A Spectrometer?

A spectrometer is an instrument that scientists use to determine information about an object or substance through the analysis of its light properties.

With its help, any unknown compositions are broken down into basic elemental components or lights emitted from far away galaxies can be used to determine information about space objects, including their size and speed.

Further, it can split up white light and measure individual narrow bands of colour. That is referred to as a spectrum, in visible light. On the other hand, a mass spectrometer measures the spectrum of the masses of the atoms or molecules present in a gas. Now let us discuss the types and usage of Spectrometer.

History of  Spectrometer

It all started since 300 BC when Euclid began work with spherical mirrors. In the late 17th century, Isaac Newton introduced the word spectrum. In order to describe the range of colours made by scattering light through a prism.

Early 19th century, witnessed the first spectrometers began appearing by many scientists. In older times spectrometers used a small slit and lens. One that passed light through a prism to refract the light into a spectrum projected through a tube for analysis.


Types of Spectrometer

1) An Optical spectrometer- The intensity of light as a function of wavelength or of frequency. Moreover, deflection is caused either by refraction in a prism or by diffraction in a diffraction grating. These spectrometers utilize the phenomenon of optical dispersion.

2) A Mass spectrometer- It is an instrument that helps to identify the amount and type of chemicals present in a sample.  By measuring the mass-to-charge ratio and abundance of gas-phase ions.

3) A Time-of-flight spectrometer- The energy spectrum of particles of known mass can also be measured by determining the time of flight between two detectors (and hence, the velocity) in a time-of-flight spectrometer.

4) A Magnetic spectrometer- It is a device which is useful in measuring the momentum of charged particles. Or their distribution of intensity versus momentum. Similarly, it happens by passing the particles through a magnetic field. It bends their paths in proportion to their momentum.

Parts of Spectrometer

  • The Rhea – It is a flexible spectroradiometer platform.
  • The Filters – It is a filter wheel with four neutral density (ND) filters of varying optical densities (OD1, OD1.3, OD2, and OD3) which allows the instrument to operate at low luminance up to very high brightness levels.
  • The Slit – The slit allows light to enter the spectrometer and controls the resolution.
  • The Concave Mirror – It reflects the beams of light, altering their path to make them as close to parallel as possible before they reach the diffraction grating.
  • The Diffraction Grating – It splits the light and disperses individual spectral.
  • The Detector – also known as Charge Coupled Device (CCD)

Function of Spectrometer

Firstly, we need to pass the light through a spectrometer. It then breaks the light into its spectral components. After that, they then digitize the signal as a function of wavelength, and read it out and display it through a computer.

Moreover, the initial process is to direct light through a fibre optic cable into it through a narrow aperture known as an entrance slit.

The slit controls the light as it enters it. Thus, the width of the slit affects resolution; the narrower the slit, the higher the resolution.

In most of them, collimation of the divergent light occurs by a concave mirror and directed onto a grating. Consequently, grating disperses the incoming radiation and then disperses each of the individual spectral elements by wavelength, projecting them onto a detector via the second concave mirror.

Uses of Spectrometer

Some of the major applications include the following:

  1. Monitoring dissolved oxygen content in freshwater and marine ecosystems
  2. Studying spectral emission lines of distant galaxies
  3. Characterization of proteins
  4. Space exploration
  5. Respiratory gas analysis in hospitals
  6. Pharmaceutical analysis – Drug discovery and absorption, distribution, metabolism, etc.

Question for you

Q. Who invented the spectrometer and why?

Ans- German chemist Robert Wilhelm Bunsen and the German physicist Gustav Robert Kirchhoff invented it in 1859. Similarly, it was made to identify materials that emit light when heated thus knowing their composition and energy levels.

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