How to Find the Interatomic Distance in Graphite from Electron Diffraction Data?

Click For Summary

Discussion Overview

The discussion revolves around determining the interatomic distance between carbon atoms in graphite using electron diffraction data. Participants explore the application of Bragg's law for interplanar distances and seek methods to derive interatomic distances from experimental measurements, including voltage and diffraction ring diameters.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests using Bragg's law (2dsin(theta) = n(lamda)) to find the interplanar distance "d" between layers of graphite but questions how to find the interatomic distance "a" between carbon atoms within the same plane.
  • Another participant indicates that determining the interatomic distance requires more than just one diffraction ring and emphasizes the need to calculate the structure-factor based on graphite's symmetry.
  • There is mention of the bond angles in graphite being 120 degrees and an approximate interatomic distance of 0.142 nm, but the participant expresses uncertainty about how to derive this from experimental data alone.
  • A participant notes having two diffraction ring radii but is confused about the significance of having two rings and how they relate to the structure of graphite.
  • Participants discuss the hexagonal structure of graphite and its implications for determining interatomic distances, but clarity on the method remains elusive.

Areas of Agreement / Disagreement

Participants do not reach a consensus on how to derive the interatomic distance from the available experimental data. Multiple viewpoints and methods are proposed, but the discussion remains unresolved.

Contextual Notes

Limitations include the reliance on specific experimental variables (voltage and diffraction ring diameters) without a clear method for extracting interatomic distances. The discussion also highlights the complexity of graphite's structure and the need for a deeper understanding of its symmetry.

quietrain
Messages
648
Reaction score
2
ok, i did a lab and found values of the diameter of the electron rings after diffraction from a graphite. i also have the voltage that i accelerate the electrons to hit the graphite.

so to find the distance between adjacent planes of graphite carbon "d", we use bragg's diffraction law right? 2dsin(theta) = n(lamda)

but the problem is what if i need to find the interatomic distance "a" between the carbon atoms on the same plane. is there some sort of equation or law i can use to find this distance from the experiment data that i obtained above? i don't seem to recall any.

and also, am i right to say, the outer diffraction ring is caused by the diffraction between atoms of the same plane (interatomic) whereas the inner diffraction ring is caused by the diffraction between layers of atoms "d" given by bragg's law?

thanks a ton!
 
Physics news on Phys.org
maybe i rephrase my question

ok, we use bragg's law to determine the spacing d between LAYERS of graphite

but how do we determine the interatomic spacing A between the individual Carbon atoms for each plane of individual graphite?

anyone knows?
 
Last edited:
quietrain,

Graphite is pretty simple when it comes to determining the structure-factor. I won't solve the problem for you, but try to represent graphite in terms of a orthorhombic unit-cell with a multi-atom basis. Find the structure-factor based on that symmetry. There is no easy "plug and chug" answer for this problem. Your going to need to do some work!

modey3
 
er i know the bond angles are 120 and the interatomic distance is around 0.142nm. but how do i get the interatomic distance from an experiment? i only have values for voltage, and the electron ring diffraction diameter only?

so with this 2 variables, i can find the interplanar distance d using bragg's law. but what about the interatomic distance? can i find it from just those 2 variables?
 
quietrain,

You will need to use more than just one diffraction ring to determine the inter-atomic distance. That's why you need to determine the structure-factor.

modey3
 
oh ya... i have 2 radius of diffraction rings... one bigger than the other... but i don't understand why there are two?

what is the structure? i only know that graphite is hexagonal in shape, so they have bond angles of 120?

but how does that allow me to find the interatomic distance?
 

Similar threads

Graduate Electron diffraction experiment
  • · Replies 5 ·
Replies
5
Views
3K
Graduate Electron Diffraction, and General X-Ray (EBSD- Kikuchi lines)
  • · Replies 3 ·
Replies
3
Views
2K
Engineering Determining the Bragg plane spacing from diffraction pattern
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad How Does Bragg's Diffraction Apply to FCC Lattices?
  • · Replies 1 ·
Replies
1
Views
6K
Undergrad Diffraction Definition & Common Examples
  • · Replies 1 ·
Replies
1
Views
5K
Electron Diffraction: Calculate Crystal Plane Spacing
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Calculation of InAS WurtZite bragg peak position
  • · Replies 2 ·
Replies
2
Views
3K
Why Does My Calculation for Electron Diffraction Not Match the Expected Result?
  • · Replies 8 ·
Replies
8
Views
6K
Diffraction Gratings: Calculating Wavelength for CD ROM
  • · Replies 6 ·
Replies
6
Views
2K
X-Ray Diffraction Homework: Deriving (2theta) Values
  • · Replies 1 ·
Replies
1
Views
4K