2021

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Electron Affinity Measurement of Hydrogen Negative Ion by Photodetachment Microscope A Theoretical Study
(UMT, Lahore, 2021) MUHAMMAD USMAN GHANI
In this research work I calculate electron affinity of hydrogen negative ion near a reflecting wall by using the well-known Einstein’s photoelectric effect. A LASER light of certain frequency has been incident on H− and two waves are observed, one is direct wave emitted directly from H− and second is coming back after striking with the reflecting wall called indirect wave. When these waves are superimposed then an interference pattern is observed. It has been observed that the interference pattern not only depends upon electron energy but also the distance between ion and surface. Using theoretical imaging method I study the interference pattern for different incident energies and plot graphs and draw Newton rings by using Matlab coding. Then I derive a linear relation between incident energy and square of number of Newton rings and by plotting this relation, this enables me to calculate the electron affinity of hydrogen negative ion.