TEACHING DEMONSTRATION OF SPECTRUM BROADENING IN TWO-PHOTO TRANSITION OF RB

The measurement of atomic spectrum is an important tool to reveal the microscopic structure and pattern of motion of microscopic particles. Therefore, the teaching of related fields is involved from undergraduate to graduate stage, especially the teaching of spectroscopy. However, nonuniform broadening caused by Doppler effect and uniform broadening caused by atomic collision greatly limit the resolution of the spectral lines. In the development of science and technology, in order to obtain higher resolution, it is necessary to eliminate the broadening of atomic spectral lines. In the related teaching, two-photon transition in the alkali metal atomic system has become an effective way to study the broadening mechanism due to its excellent energy level characteristics. In the current undergraduate teaching, there is a lack of demonstrations of various atomic line broadening mechanisms besides Doppler broadening. In this paper, the rubidium atom 5S_1/2→5P_3/2→5D_5/2 two-photon transition spectral line is employed to measure the half-width change caused by changing the laser power, the temperature of the atomic cell and magnetic field strength. While verifying the two-photon transition, it focuses on demonstrating the mechanism of the atomic spectral line broadening and the measurement method of the half-width of the spectral line. Through this experiment, on the one hand, undergraduate students can grasp the relevant knowledge of atomic spectral line broadening and two-photon transition and understand the connotation of theoretical knowledge more deeply, and on the other hand, they have trained their hands-on ability by building experimental instruments independently, which is particularly important for improving the quality of undergraduate students majoring in physics. The experimental device shown in this paper is simple, easy to build, and suitable for classroom demonstration and experimental teaching.