My thesis is divided in two principal parts: Theoretical and experimental. In the theoretical part we have calculated the potential energy curves of the CsAr system using an ab into technique and a pseudopotential approximation to solve the corresponding Schrodinger equation. In this part we have seen that the potential energy curves are constituted of three regions: repulsive, stability and attractive ones. From this study we have extracted some spectroscopic parameters of the CsAr calculate the D2 and D1 line wavelength. We found that for the ground state, X2∑1/2, a potential well of 25.10-5a.u. deep located at an interatomic distance of9.75 a.u. For the first excited state, A2π1/2, a well of 73.2a.u. located at 129.10-5a.u. For the experimental part, first we have installed an atomic emission/absorption experiment in the physics department of King Khaled University of Abha. Second we have used this bench for studying the CsAr system function of different parameters. During this part we have focalized our attention to the blue wing emission versus temperature, relaxant agent such as buffer gas pressure and ethane, and laser intensity..