Saturday 27 April 2024

Blue skies and brilliant sunsets: Application of Raman spectroscopy in microbiology

 Microbial world. Image designed by Tim Sandle

Raman spectroscopy is based on the scattering of laser light in order to probe a molecular structure. As millions of photons are scattered, individual photons will interact with the vibrational states of the sample molecule and emit light of a different wavelength. This enables a sample to be detected and characterized through the generation of a spectral fingerprint. The level of detail is down to variations in the heterogeneities within a microbial population (1).


Before launching into the science, technology and application in microbiology, let’s consider what is happening in everyday terms. It is important to first note that the efficiency of a photon's scattering depends on its wavelength. Now let’s ask ourselves “why is the sky blue?”


The blue color of the sky during the day (at least in the summer) as a result of the scattering of light by dust, water vapor etc. We see the sky as blue during the day because violet and blue light scatter more than other, longer wavelengths of light.


If we are then lucky to observe a spectacular sunset, the sun may appear red at sunset since red light scatters less efficiently and is more likely to pass through the atmosphere than other wavelengths of light.

In both cases, we have inelastic scattering of photons. 


This week’s article explains Raman spectroscopy and looks at its applications for microbiology: (opens in LinkedIn).


Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (

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