New features in Franck–Hertz experiment with argon: experiment and Monte Carlo simulation

• Published in: European journal of physics 2024-07, Vol.45 (4), p.45206
• Main Authors: Dong, Tianzuo, Wang, Yanqi, Zhang, Yi, Shi, Qingtian, Dai, Rucheng, Sun, Xiaoyu, Wang, Zhongping, Zhang, Zengming, Sun, Lazhen
• Format: Article
• Language: English
• Subjects: electron-argon collisions; Franck–Hertz experiment; higher excitation state; Monte Carlo simulation
• ISSN: 0143-0807; 1361-6404
• DOI: 10.1088/1361-6404/ad5807

In this work, a homemade apparatus was built to perform the Franck–Hertz experiment with argon. The lowest energy state and the higher energy state of argon can be excited by the Franck–Hertz experiment. The excitation energies of the argon atom are measured by using the setup. The obtained higher excitation energy of argon atoms is 13.73 ± 0.28 eV, for the mixture of higher energy states 3 s 2 3 p 5 3 d and 3 s 2 3 p 5 4 p . A plate capacitor model was constructed to simulate the inelastic collisions between electrons and argon atoms using the Monte Carlo method. The simulated current curve and electron energy distribution agrees with that of Franck–Hertz experiments, especially the features of higher excited state. The Monte Carlo simulation indicates the deformed electron energy distribution results from the change in excitation proportion of energy levels during the collisions of electrons and argon atoms. Moreover, the new features in Franck–Hertz curve are ascribed to the higher excitation states of argon atoms. The experimental setup has been applied to undergraduate physics experiment teaching in college. Students can perform the Franck–Hertz curve measurement of not only the lowest excited state, but also the higher excited states of argon. In addition, students can do the Monte Carlo simulations for the experimental Franck–Hertz curves and gain a better understanding of electron-argon atom collisions in the experiment. The new designed experiment will make students more familiar with the quantum behavior in atomic physics and quantum mechanics course.