Can we distinguish multilayer graphene with bulk graphite flake?
I have an AFM result of 4-8 nm but raman peak intensity ratio I2D/IG is almost same of 0.4-0.5.
It shows a shift in 2D peak of almost 20cm-1.
Is this shift sufficient to say that it has thinned down to multi layer or should i change my terminology from multilayer to graphene nanosheet.
Can anyone explain this?
Additionally, you can calculate the ratio of ID/IG, which should be around 0.18 for multilayer graphene. The calculation of number of layers by G band position can also help you to estimate your hypothesis.
wG=1581.6+11/(1+n^1.6) where wG is the G band position and n is the no of layers.
Dear Dharmendra,
Could you please provide reference for the following equation that you mentioned?
wG=1581.6+11/(1+n^1.6)
Thank You all,
Dear Dharmendra ,
ID/IG is supposed to give details regarding quality of the graphene . If i have large basal defects present in my sample and also edge defects, this vary ID/IG and so can this ID/IG can it give details on layer number. An equation derived with G peak position can vary according to stress in the sample. If so the initial G peak position can vary. My doubt is , considering this , is this equation valid for all kinds of exfoliation?
Dear Tabassum,
Reference you asked for the equation is given below :
Wang H, Wang Y, Cao X, Feng M, Lan G. Vibrational properties of graphene and graphene layers. J Raman Spectroscopy. 2009;40(12):1791–6. doi: 10.1002/jrs.2321
Hi Christian Punckt,
Thanks a lot for your reply: I went through the ISO standardized vocabulary and it says upto 10 layers as few layer graphene.
It also says Graphene Nanoplatelets - GNPs typically have thickness of between 1 nm to 3 nm and lateral dimensions ranging from approximately 100 nm to 100 µm. So Graphene nanoplatelets also have below 10 layers right. Does it say anything about graphite nanoplatelet?
https://www.iso.org/obp/ui/#iso:std:iso:ts:80004:-13:ed-1:v1:en
Wazeem:
It's clear you have a bulk graphite flake in your AFM result. But as for the Raman method, I would simply refer you to a 2006 paper by Ferrari, et. al on "Raman Spectrum of Graphene and Graphene Layers".
Here's the DOI:
Article Raman Spectrum of Graphene and Graphene Layers
and, I've uploaded the paper FYI as well. In this technique, you should be paying attention to the shift of the peaks as a function of thickness. This shift occurs fundamentally due to the Pi-Pi stacking (and interaction) of the graphene sheets. When there is but a single sheet, there is no Pi-Pi interactions and no shift.
I hope this helps!
It is difficult to distinguish the multi-layers graphene (more than 10 layers) and bulk graphite by using Raman spectroscopy. Raman spectroscopy is reliable up to a maximum of 5-7 layers. I think AFM height measurement can provide exact no. of layers in graphene sheets.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials
- Carbon Materials
- Graphite
- Graphene