Hi all who are studying graphene.
Anyone know why absorption coefficient for graphene is not fixed value when we calculate graphene concentration?
I know that it is calibrated value with absorbance/length and graphene concetration.
I want to get concentration of unknown graphene dispersion with Uv-vis, if it has certain fixed absorption coefficient.
But if it has different value depending on graphene layer, size and functional group, how can I know graphene concentration?
Do you guys usually filtrate and weigh that mass and disperse in known volume DI?
what else do you use to calculate graphene concentration when is very low concentration?
Well you are right, absorption coefficient comes from relation between pathlenght, absorption and concentration. It is Lambert-Beer Law.
I am not quite sure what do you mean when you say that coeff is different, but it should behave as described in attachment. And an average absorption coefficient of
lambda=660 nm should be equal to: 2,460 L g-1 m-1.
Dear Peter,
I tried to ask why graphene has different absorption coefficient. I found out that absorption coefficient is bit different with each paper. I found one paper which shows relation between absorption coefficient and layer, size, functional group.
To Beata
Thanks for your kindness. I had read that paper and read some other papers which have different absorption coefficient such as two paper that I attach. it has absorption coefficient value 3620ml/mg*m.
I want to get concentration of unknown graphene dispersion with Uv-vis, if it has certain fixed absorption coefficient. But if it has different value depending on graphene layer, size and functional group, how can I know graphene concentration? Do you guys usually filtrate and weigh that mass and disperse in known volume DI?
I think this link is useful,
http://www.instanano.com/characterization/theoretical/concentration-calculation-from-uv-vis-absorbance/
Maybe the experimentally determined value is not only 'absorption' but also scattering and shading. Graphene is not in solution but in dispersion.
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