determination quantique de spectre d'absorption du systeme forme par l'ion alcalino-terreux ca+ perturbe par les atomes d'helium he

Abstract

Abstract In this thesis we are interested in the quantum study of the calculations of the pressure broadening of the H(4s (_^2)S_(1/2) -4p (_^2)P_(1/2) ) and K(4s (_^2)S_(1/2) -4p (_^2)P_(3/2) )lines under the influence of binary collisions between calcium 〖Ca〗^+ions and helium Heatoms. The potential energy curves of the 〖Ca〗^+-He system have been calculated and we are focused on constructing accurate curves for the potential energy of the ground states X (_^2)Σ_(1/2)^+ and the excited states D (_^2)Π_(1/2) , D (_^2)Π_(3/2) and E(_^2)Σ_(1/2)^+ , in addition we evaluated transition dipole moments using ab − initio methods based on RCCSD(T) and SA − CASSCF/MRCI calculations that include spin-orbit effects with Davidson and BSSE corrections. We also determined the permanent electric dipole moments PDMs, vibration levels and lifetime. The absorption coefficients are determined at wavelengths of 200 to 500 nm and at temperatures of 4000 to 12000 K. The theoretical profile reveals that free-free transitions are dominant. Presence of the satellite peak in the red wing near the 436nm wavelength position results from the contribution of the D (_^2)Π_(1/2) ←X (_^2)Σ_(1/2)^+ and D (_^2)Π_(3/2) ←X (_^2)Σ_(1/2)^+ transitions. Our results are compared to previous theoretical and experimental results. Keywords: pressurebroadening,potential energy curves,transition dipole moments,permanent electricdipole moments,absorption coefficients