The purpose of this qualitative introduction to the Raman effect is to present the essential theory of inelastic scattering of light compatible with the minimum of knowledge acquired by a final year secondary-school student. The key notions for a better understanding of the different mechanisms at the root of the light scattering - and the Raman effect - are presented in the introduction and represent the prerequisite of knowledge essential to assimilate the following chapters. It's likely that some unknown words or expressions will pose problems to some readers. Nowadays, by using the internet and Google, it's easy to find answers to such questions.
This introduction to the Raman effect remains qualitative - in the sense that it uses classical mechanics and not quantum mechanics, which are more appropriate to describe atoms and molecules and their interactions with light. Consequently, it cannot explain in depth the question about the relative intensities of the Stokes and anti-Stokes processes. A brief discussion using Maxwell-Boltzmann statistics will be presented to clarify this question of intensities.
The 3 pillars to understand the Raman effect are :
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the electronic polarizability of atoms and molecules. Occurrence of an electric dipole moment induced by the electric field component of a laser beam
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radiation across the space of electric dipole induced on the atoms and molecules by laser
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modulation of the dipole radiating the vibrations of atoms and molecules
This introduction is structured into 8 parts:
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The essential basics of light
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Introduction to Rayleigh or elastic scattering for dipolar radiation
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Introduction to Raman or inelastic scattering by considering the interaction of a harmonic oscillator with dipolar radiation
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A brief history about the discovery of the Raman effect
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Various spectrometers devoted to Raman spectroscopy
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Practical use of Raman with a microscope (Raman microprobe)
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What information is obtained from a Raman spectrum?
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Applications of Raman scattering in the UV and visible light range for the nanoworld (physics, chemistry, biology).
Armed with this base knowledge, physicists, chemists, biologists and forensic experts will be able to take up with more confidence the various books dealing with the light scattering as a tool to investigate specific (nano) materials and processes.
St Germain en Laye January 23rd 2009
Bobrowniki Wielkie March 6th 2009
Author : Edouard Rzepka 
Author's note
Most of these website pages have been written during a winter stay in the South of Poland, in the Małopolska, at the foot of the Carpathians, during February 2009. The "snow-covered" pages were written during snow days and remain still a little hazy !
These pages already have a history. Their creation stems from a discussion about the Raman effect with two charming young college bachelors, one of them being now a first year student at Polytechnic Krakow, and the second, a 3rd year student at the Krakow Teacher Training College. I believe that I have succeeded to explain them the Raman effect and I hope that you will be also satisfied by this tutorial.
Acknowledgments
I would like to express my gratitude towards Dr Yves Marfaing Ph.D. and Dr Simon FitzGerald Ph.D. for giving me advice and correcting the French and English version.
I would like also to express my gratitude towards Ing-webmaster Jean-Charles Ricquier from the CNRS IMN for giving me advice about the website presentation and suggesting some new javascripts.
This website has seen the light thanks to a financial support from HORIBA Scientific and I wish to thank Madame Sophie Morel for this sponsorship.
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