Electron Diffraction through a Graphite Film
Paper
Electron diffraction through a graphite film.
Mark Raskin Skidmore College (11/14/14)
Abstract: In this paper, the wave-like properties of electrons are discussed. We are trying to measure the inter-atomic spacing (d) between the graphite atoms, which we are accelerating electrons through. As the electrons pass through the graphite, an interference pattern emerges on the screen in front of the gun. The interference pattern shows up as a circle within a circle, each of which represents a different interatomic spacing in the graphite lattice structure. As we increase the voltage of the potential difference in intervals of .5kV from 2.5kV to 4.5kV, the diameter of the interference pattern will decrease. We did this several times and found that the inter-atomic spacing between the lattice structures of the graphite are 2.51Å and 1.31Å, with errors of 17.8% and 6.5% respectively compared to the accepted values of 2.13Å and 1.23Å.
1. INTRODUCTION
Electron diffraction is just one example of how a particle can act like a wave. Diffraction is the idea that a wave will change direction when it encounters a sharp edge or a slit. In this experiment, we are using an electron gun to shoot a beam of electrons at a thin layer of graphite whose atoms are arranged in a hexagonal shape, allowing for diffraction between the individual atoms. Constructive interference will occur when
(1)
The electron gun uses a potential difference of between 2.5-4.5kV to accelerate the electrons through the graphite sheet at a screen at the other side of the evacuated gas bulb. We can determine the distance between the different spacing of the carbon atoms by determining the diameter of the circles in the interference pattern. As the electrons pass
through the graphite sheet, they bend at an angle θ and will create rings of diameter D,
(2) where L is the distance from the graphite layer to the screen. As you increase the accelerating voltage, the
Electron diffraction through a graphite film.
Mark Raskin Skidmore College (11/14/14)
Abstract: In this paper, the wave-like properties of electrons are discussed. We are trying to measure the inter-atomic spacing (d) between the graphite atoms, which we are accelerating electrons through. As the electrons pass through the graphite, an interference pattern emerges on the screen in front of the gun. The interference pattern shows up as a circle within a circle, each of which represents a different interatomic spacing in the graphite lattice structure. As we increase the voltage of the potential difference in intervals of .5kV from 2.5kV to 4.5kV, the diameter of the interference pattern will decrease. We did this several times and found that the inter-atomic spacing between the lattice structures of the graphite are 2.51Å and 1.31Å, with errors of 17.8% and 6.5% respectively compared to the accepted values of 2.13Å and 1.23Å.
1. INTRODUCTION
Electron diffraction is just one example of how a particle can act like a wave. Diffraction is the idea that a wave will change direction when it encounters a sharp edge or a slit. In this experiment, we are using an electron gun to shoot a beam of electrons at a thin layer of graphite whose atoms are arranged in a hexagonal shape, allowing for diffraction between the individual atoms. Constructive interference will occur when
(1)
The electron gun uses a potential difference of between 2.5-4.5kV to accelerate the electrons through the graphite sheet at a screen at the other side of the evacuated gas bulb. We can determine the distance between the different spacing of the carbon atoms by determining the diameter of the circles in the interference pattern. As the electrons pass
through the graphite sheet, they bend at an angle θ and will create rings of diameter D,
(2) where L is the distance from the graphite layer to the screen. As you increase the accelerating voltage, the
References: [1] J. Linz, “Electron Diffraction Lab Handout,” (2014) [2] 3B Scientific® Physics, “Electron Diffraction Tube S 1013889 equipment manual”