Raman spectroscopy is Single molecule identification

In summary: The scattering cross-section is a measure of how well the experimental signal is distinguished from the background noise. With a small scattering cross section the experiment would take ages or fail totally as the relevant information would get buried into the background.
  • #1
photon79
60
0
Raman spectroscopy is "Single molecule identification"

Hi , I heard that the speciality of Raman spectroscopy is "Single molecule identification", it'd be really great if somebody can tell me HOW! because its surely going to be a question in my exam!
Thanks in advance.
 
Physics news on Phys.org
  • #2
Raman scattering excites low energy vibrational and rotational modes which are very target specific. I guess that's how the molecules are indentified. Someone else can probably give you more info because I only have limited knowledge on X-ray Raman scattering and it seems you're asking about Raman scattering around the laser region.
 
  • #3
Thnks inha,,you are right, I was looking in laser excitations.
 
  • #4
What do you mean by single-molecule identification. Do you mean that a sample can be identified with only a single-molecule present?

Claude.
 
  • #5
Claude Bile said:
What do you mean by single-molecule identification. Do you mean that a sample can be identified with only a single-molecule present?

Claude.

That is what I want to know,i think it is not same as you said but it is connected with the Surface enhanced Raman spectroscopy(I think).
It might be identifying a given unknown sample using info about its symmetry !
 
  • #6
Yes, SMD (single molecule detection) is done using SERS. The reason you need SERS is scattering cross-section. With regular Raman scattering, the cross-section is typically of order 10^{-30] cm^2. With SERS, you get as much as about 10^{-15} cm^2 (or thereabouts).
 
  • #7
Gokul43201 said:
Yes, SMD (single molecule detection) is done using SERS. The reason you need SERS is scattering cross-section. With regular Raman scattering, the cross-section is typically of order 10^{-30] cm^2. With SERS, you get as much as about 10^{-15} cm^2 (or thereabouts).

Ok , Thanks Gokul!
I dodn't get what scattering cross section has to do with molecule identification, more info please! (or any web site?)
 
  • #8
With a small scattering cross section the experiment would take ages or fail totally as the relevant information would get buried into the background.
 
  • #9
Exactly, larger scattering cross-section = more scattered photons = greater signal-to-noise ratio.

Claude.
 

1. What is Raman spectroscopy and how does it work?

Raman spectroscopy is a technique used to study the vibrational modes of molecules. It works by shining a laser on a sample and measuring the scattered light. The scattered light will have a slightly different frequency than the incident light, which provides information about the molecular bonds in the sample.

2. How does Raman spectroscopy allow for single molecule identification?

Raman spectroscopy allows for single molecule identification by providing a unique vibrational fingerprint for each molecule. This fingerprint can be used to identify the molecule and distinguish it from other molecules in the sample.

3. What are the advantages of using Raman spectroscopy for single molecule identification?

Raman spectroscopy has several advantages for single molecule identification. It is non-destructive, meaning the sample is not altered or damaged during analysis. It also has a high sensitivity, allowing for the detection of very small amounts of a molecule. Additionally, Raman spectroscopy can be used to identify molecules in a variety of environments, including solid, liquid, and gas phases.

4. What are the limitations of using Raman spectroscopy for single molecule identification?

One limitation of Raman spectroscopy is that it can only identify molecules that have a Raman-active vibrational mode. This means that molecules with symmetric bonds, such as diatomic molecules, are not suitable for Raman spectroscopy. Additionally, Raman spectroscopy is not as sensitive as other techniques, such as mass spectrometry, and may not be able to detect very low concentrations of a molecule.

5. How is Raman spectroscopy used in real-world applications for single molecule identification?

Raman spectroscopy has a wide range of applications in various fields, including pharmaceuticals, forensics, and environmental monitoring. It can be used to identify unknown substances, analyze the composition of a sample, and monitor chemical reactions. In the pharmaceutical industry, Raman spectroscopy is used for drug discovery and development. In forensics, it can be used to identify trace evidence. In environmental monitoring, it can be used to identify pollutants in air and water samples.

Similar threads

  • Atomic and Condensed Matter
Replies
1
Views
1K
  • Atomic and Condensed Matter
Replies
3
Views
2K
Replies
3
Views
11K
  • Quantum Physics
Replies
2
Views
737
  • Atomic and Condensed Matter
Replies
1
Views
1K
  • Atomic and Condensed Matter
Replies
0
Views
282
  • Chemistry
Replies
5
Views
3K
  • Atomic and Condensed Matter
Replies
5
Views
5K
  • Atomic and Condensed Matter
Replies
2
Views
4K
  • Atomic and Condensed Matter
Replies
1
Views
1K
Back
Top