What is the difference between fluorescence and Raman scattering?

Fluorescence occurs due to real electronic transitions. On the other hand, Raman scattering occurs as a result of virtual electronic-vibrational transitions . More generally, we can say that fluorescence is an absorption or re-emission process and Raman scattering is an inelastic scattering process.

What are the fundamental differences between the Raman spectroscopy and fluorescence spectroscopy?

The main difference between Raman scattering and fluorescence is the excited state lifetime. Fluorescence excited states are longer-lived than the ‘virtual’ states associated with Raman scattering. In fluorescence, absorption of light excites an electron to a higher energy state.

How can we differentiate fluorescence and Raman Stokes lines?

In simple words, in Fluorescence exciting photons as well as emitted photons have exactly same wavelengths. However in Raman scattering the emitted photons have slightly different wavelengths which is usually given by wavenumber difference.

What is Raman spectroscopy and how does it differ from Raleigh scattering spectroscopy?

Raman spectroscopy measures the scattering of light by matter. The light source used in Raman spectroscopy is a laser. This is called Rayleigh scattering. Sometimes, however, the scattered (emitted) light is of a slightly different frequency than the incident light.

What is Raman scattering in fluorescence?

When a fluorescent sample is excited in a spectrometer, four processes can occur to the photons of the excitation light: absorbed by the sample and remitted as fluorescence, transmitted through the sample, scattered elastically, or scattered in-elastically which is more commonly known as Raman scattering.

What is the difference between Raman spectroscopy and resonance Raman spectroscopy?

Resonance Raman spectroscopy has greater sensitivity compared to its non-resonance counterpart. It is capable of analyzing samples with concentrations as low as 10-8 M. Non-resonance Raman can analyze samples with concentrations no lower than 0.1 M.

What is fluorescence in Raman Spectroscopy?

The fluorescence interference in Raman spectroscopy may result from the compound analysed or from fluorescent impurities in the sample. It is an absorption process that causes molecules to be excited to a higher electronic state, which requires high-energy photons.

What are Stokes and anti Stokes lines in Raman scattering?

Stokes lines are of longer wavelength than that of the exciting radiation responsible for the fluorescence or Raman effect. Anti-Stokes lines are found in fluorescence and in Raman spectra when the atoms or molecules of the material are already in an excited state (as when at high temperature).

How do you distinguish fluorescence peak from Raman peak?

The classic way to check whether a peak is part of the fluorescence spectrum or a Raman artefact is to vary the excitation wavelength. Fluorescence and Raman scattering are fundamentally different processes and respond differently to changing the excitation wavelength.

What is Rayleigh in Raman Spectroscopy?

The first type of scattering, Rayleigh scattering, is an elastic scattering process in which a photon bounces off a molecule like a billiard ball, emerging with the same energy as it entered. For approximately one million photons Rayleigh scattered by a molecule, only one photon is Raman scattered.

Which type of scattering is the strongest?

Another finding is that forward scattering is stronger than backward scattering, because the relative phase differences of contributions from different scattering locations on the particles become smaller.

What is Rayleigh scattering in fluorescence?

Rayleigh scattering refers to the elastic scattering of light or dispersion of electromagnetic radiation by particles. It is a common phenomenon contained in fluorescence spectra occurring in the region where the excitation (EX) wavelengths are close to the emission (EM) ones.