Raman spectroscopy is Single molecule identification

Click For Summary

Discussion Overview

The discussion centers around the concept of single molecule identification using Raman spectroscopy, specifically exploring the mechanisms and conditions that enable this capability. Participants inquire about the principles behind Raman scattering and its application in identifying molecules at the single-molecule level.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that Raman scattering excites low energy vibrational and rotational modes, which may contribute to molecule identification.
  • There is a question about the meaning of "single-molecule identification," with one participant seeking clarification on whether it refers to identifying a sample with only a single molecule present.
  • Another participant connects single-molecule identification to Surface Enhanced Raman Spectroscopy (SERS), proposing that it might involve identifying an unknown sample using information about its symmetry.
  • Some participants mention that single molecule detection (SMD) is achieved using SERS due to the significantly larger scattering cross-section compared to regular Raman scattering.
  • Concerns are raised about the implications of a small scattering cross-section on the feasibility of experiments, suggesting that it could lead to poor signal detection.
  • Participants discuss that a larger scattering cross-section results in more scattered photons, which enhances the signal-to-noise ratio.

Areas of Agreement / Disagreement

Participants express varying interpretations of single-molecule identification and the role of SERS in this context. There is no consensus on the exact mechanisms or definitions, indicating multiple competing views remain.

Contextual Notes

Some assumptions about the definitions of terms like "single-molecule identification" and "scattering cross-section" are not fully clarified, which may affect the understanding of the discussion.

photon79
Messages
60
Reaction score
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
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.
 
Thnks inha,,you are right, I was looking in laser excitations.
 
What do you mean by single-molecule identification. Do you mean that a sample can be identified with only a single-molecule present?

Claude.
 
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 !
 
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).
 
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?)
 
With a small scattering cross section the experiment would take ages or fail totally as the relevant information would get buried into the background.
 
Exactly, larger scattering cross-section = more scattered photons = greater signal-to-noise ratio.

Claude.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 3 ·
Replies
3
Views
13K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 5 ·
Replies
5
Views
6K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 3 ·
Replies
3
Views
5K
  • · Replies 0 ·
Replies
0
Views
3K
  • · Replies 7 ·
Replies
7
Views
8K
  • · Replies 7 ·
Replies
7
Views
7K