What is a spectrophotometer and what are its types

What is a spectrophotometer and what are its functions

A spectrophotometer is an instrument that can be used to measure the amount of light that passes through it, it measures the intensity of light as a function of its wavelength. This device is important to determine the unknown substances and for calculating the concentration of known substances. Spectrometers are commonly used to measure light absorption. It is a photometric device that measures spectral transmittance and spectral reflectance relative spectral emittance. It compares the light leaving from an object with that incident on it at each wavelength. Spectrometers are available in different shapes and size, the two main categories of the spectrometer are single beam and double beam. Spectrometers are widely used not only in the field of physics but it is also used in other fields such as chemistry, biology, and biochemistry.

How does a spectrophotometer work

A spectrophotometer works by passing white light through a prism-like device it is called a diffracting grating and during this process, the light will break up into colors of the rainbow. The diffracting grating can be rotated in order to pass the particular color through a narrow slit avoiding other colors. After that light passes through a tube that contains a colored solution and the tube is called ‘cuvette’ which contains a colored solution and the lights which are not absorbed by the sample then hit the photoelectric cell which in turn produces an electric current. If the light which enters the sample is high, then the current produced will be high too. The amount of light getting through the solution is called the transmittance and the amount of light which is absorbed by the sample is called absorbance.

What are the difference between a single beam and double beam spectro-photometers

Spectrophotometer which is a single beam measures the light intensity but the double beam measures the intensities of light on two separate paths. Single beam spectrometer is used widely because it is difficult to recombine the light beam prior to reaching the monochromator with the double beam spectrometer

What are the components of spectrophotometer

The parts of single beam spectrophotometers are

Light source – Light source is used to transmit the light, which has all frequencies in the visible light spectrum. Mostly the light source is a normal light bulb, in case of special wavelength reading the light source will be UV bulb.

Monochromator – Monochromator does the filtering of the light, by selecting one frequency of the light which is specified by the user.

Aperture – It is used to direct the specified wavelength to a part of the sample, this will help to eliminate the errors in uneven sample distribution.

Cuvette – This is used to hold the sample, mostly it is made up of plastic

Sample – It is the solution which the user selected to quantify, some spectrophotometers are capable to quantify solid or gas mixtures.

Photoresistor – photoresistor detects the intensity of the light which is transferred through the sample it is an electrical device.

Prism – prism is an optical element that is transparent and it refracts light, mostly they are made up of glass, plastic, and fluorite. Mostly it would be in a triangular shape and it has a flat polished surface and the flat surfaces would have an angle between them.

Diffraction grating – this component is used to split and diffract the lights, then the light will split up as the color of the rainbow, this can also select a particular color and avoid other colors according to the users choice

Output device – it is a computer screen that will display the values for the user, it has a separate operating system from the spectrophotometer but both of them are internally connected and the output information from the spectrophotometer would be saved in the computer.

What are the types of spectrophotometers

Atomic absorption spectrophotometer – These devices are used to determine the concentration of a particular metal in a sample.

Fluorescent spectrophotometer – These are mostly used for high sensitivity and selectivity. This type uses a special light source and high brightness and longer life.

UV spectrophotometers – These spectrophotometers use UV light of wavelengths from 200 to – 350nm. These equipment have high-end microprocessor control technology. That can be used for various researches.

Visible range spectrophotometer - These spectrophotometers use visible light ranges from 350 to 700nm wavelength. It is used for the quantitative estimation of various analytes such as biological macromolecules, and organic molecules…

What are the applications of spectrophotometer

  • Spectroscopy
  • Thin-film characterization
  • Color matching
  • Optics
  • Chemical analysis
  • They are also used in industrial applications like printing and forensic examination