Spherical-tensor treatment of coherent transients

I present a spherical-tensor treatment of coherent transient effects induced in atoms by an optical pulse resonant with a dipole transition. The resonant pulse is shown to excite electronic multipole moments in the atom which can be higher than the dipole. The dependence of these moments on the length and intensity of the applied pulse is derived. It is shown that information about the damping of these moments due to thermal collisions is contained in photon-echo signals