Davisson and Germer Experiment

Do you know that ‘particles’ of matter like electrons and atoms and photons of light have a dual character? Yes, it behaves like a particle at times and like a wave at other times. The Davisson and Germer experiment confirmed the de Broglie equation and established the wave nature of electrons. De Broglie discussed the dual nature of the matter in 1924, but Davisson and Germer’s experiment later confirmed the findings. This experiment will look at the scattering of electrons by a Ni crystal.

The electron beam was focused on a nickel target that could be rotated to observe the dispersed electrons’ angular dependency. Their electron detector (known as a Faraday box) was positioned on an arc and could be rotated to observe electrons from various angles. It was later discovered that the intensity of the dispersed electron beam had a peak at some angles. The Bragg law could calculate the lattice spacing in the nickel crystal based on this peak, which showed wave behaviour for the electrons. The Davisson and Germer experiment assumed that waves reflected from two different atomic levels of a Ni crystal would have a fixed phase difference. These waves would interfere either constructively or destructively after reflection. As a result, a diffraction pattern would be created. 

This post will look at how a Ni crystal scatters electrons in the Davisson-Germer experiment. The de Broglie hypothesis and its relationship to the Davisson-Germer experiment will also be discussed.

Davisson and Germer Experiment Theory

C.J. Davisson and L.H. Germer experimented in 1927 to demonstrate the wave nature of an electron. The famous Davisson Germer electron diffraction experiment was carried out due to a lack of explanation for the wave nature qualities of an atomic model. The method of electron diffraction was used to propose this.

This section goes over the experiment and how it was observed in great detail. The explanations are clear and concise to assist students in grasping the topics more quickly. This topic holds a significant amount of weight in terms of exam marks. After a thorough reading, students can quickly solve the variables and equations connected to the Davisson Germer experiment.

Davisson and Germer devised an experiment to verify de Broglie’s theory that matter behaved like waves, comparable to what would be used to study the interference pattern produced by X-rays scattering off a crystal surface. The essential concept is that the planar nature of crystal structure provides regular scattering surfaces. As a result, waves scattered from one surface can interfere constructively or destructively with waves scattered from the next crystal plane further into the crystal.

Wave Nature of Electrons

Louis de Broglie had been influenced by relativity and the photoelectric effect as a young student at the University of Paris, both of which had been introduced during his lifetime. The photoelectric effect revealed light’s particle qualities, previously overlooked as a wave phenomenon. He was curious if electrons and other “particles” have wave qualities.

Examples of Electron Waves

As predicted by the de Broglie hypothesis, the discrete atomic energy levels and electron diffraction from crystal planes in solid materials are two specific instances that support the wave nature of electrons. The electron waves in the Bohr model of atomic energy levels can be viewed as “wrapping around” the perimeter of an electron orbit so that constructive interference occurs.

When electrons are limited to dimensions of the order of an atom’s size, the wave nature of the electron must be invoked to explain their behaviour. The quantum mechanical “particle in a box” is based on this wave nature. The outcome of this calculation is used to characterise the density of energy levels for electrons in materials.

Rutherford Nuclear Model of Atom

An atom, according to Rutherford, is essentially an empty space with electrons circulating in predictable patterns around a fixed, positively charged nucleus. On that basis, he presented a model in which electrons were uniformly implanted in a positively charged matrix. The Plum pudding model was the model’s name. J.J. Thomson’s plum pudding model, however, had some flaws. It was unable to explain certain experimental data relating to element atomic structure. 

Democritus, a Greek philosopher, was the first to propose the concept of atoms in 400 BCE. However, it was not until 1803 that John Dalton offered the idea of the atom for the second time. Atoms, on the other hand, were thought to be indivisible at the time. This concept of an atom as indivisible components persisted until 1897, when J.J. Thomson, a British physicist, discovered negatively charged particles that were eventually dubbed electrons.

Results of the Davisson and Germer Experiment

Thus, from the above results of the experimental and theoretical data, we can say that there’s a similarity between the theoretical and experimental values obtained from the De-Broglie wavelength and the Davisson- Germer experiment. Thus, this experiment confirms the wave nature of electrons and, therefore, the nuclear physicist relation.

Conclusion

Particles of matter, like photons, have a dual nature: one is a particle, while the other is a wave. De Broglie devised a formula that linked their wavelength and frequency to their mass, velocity, and momentum (particle properties) (wave characteristics). In separate tests in 1927, Thomson, Davisson, and Germer demonstrated that electrons behave like waves with a wavelength that matched de Broglie’s formula.

The subject of their experiment was the diffraction of electrons through crystalline solids, in which the regular arrangement of atoms operated as a grating. Diffraction experiments with other ‘particles, such as neutrons and protons, were soon carried out and confirmed de Broglie’s formula. The wave-particle duality was confirmed in these tests.