Why is Raman weak?
Because scatter occurs in all directions, the scattered photons are measured at 90o to the incident radiation. Also, Raman scatter is generally a rather unfavorable process resulting in a weak signal.
What are the types of Raman?
To overcome these problems, different types of Raman systems have been developed. The most broadly used for biological applications are Confocal Raman Spectroscopy (CRS), Modulated Raman Spectroscopy (MRS), Surface-Enhanced Raman Spectroscopy (SERS), and Tip-Enhanced Raman Spectroscopy (TERS).
What is the Raman test?
Raman Spectroscopy is a non-destructive chemical analysis technique which provides detailed information about chemical structure, phase and polymorphy, crystallinity and molecular interactions. It is based upon the interaction of light with the chemical bonds within a material.
Does Raman measure Stokes and anti-Stokes?
Raman spectroscopy observes the change in energy between the incident and scattered photons associated with the Stokes and anti-Stokes transitions. This is typically measured as the change in the wavenumber (cm-1), from the incident light source.
What are Stokes and anti-Stokes lines in Raman spectra?
The key difference between stokes and anti-stokes lines is that stokes lines have a longer wavelength than the wavelength of exciting radiation that is responsible for the fluorescence or Raman effect, whereas Anti-stokes lines occur in fluorescence or Raman spectra when atoms or molecules are already in an excited …
Why do we use SERS?
Surface-enhanced Raman spectroscopy (SERS) is a vibrational spectroscopy technique with sensitivity down to the single molecule level that provides fine molecular fingerprints, allowing for direct identification of target analytes.
What is a SERS substrate?
What is a SERS substrate? A Silmeco SERS substrate, called a SERStrate, is essentially a silicon wafer coated with a metal like gold or silver (or a custom metal of choice). The silicon wafer is made up of a special structure – ag/au coated nano-pillars – which facilitates molecular sensing (Raman scattering).
What are the two types of Raman scattering?
Raman scattering occurs in two ways. If the emitted radiation is of lower frequency than the incident radiation, then it is called Stokes scattering. If it is of higher frequency, then it is called anti-Stokes scattering. The green arrow in the picture to the left represents the incident radiation.
What is Raman spectroscopy instrumentation?
Raman spectroscopy is a type of molecular spectroscopy that involves the dispersion of electromagnetic radiation by molecules or atoms. It measures the rotational, vibrational, and other low-frequency modes of molecules.
What is the difference between Stokes and anti-Stokes Raman scattering?