We have made a review of our works about the interaction between a two-level molecular system immerse in a solvent with time dependent electromagnetic fields. The interaction with a high intensity electromagnetic field and with a four wave mixing signal are described. The system is described using the optical stochastic Bloch equations (OSBE), where due to the collisions with the solvent the Bohr’s frequency becomes a stochastic variable. The averages of the Fourier components of the coherences are determined, employing a generalized Lorentzian approximation for the Voigt’s function as a probability distribution. Using the convolution theorem, the analytical expressions for the coherences and the optical properties associated to the molecular system are calculated. The results show the sensibility of these properties with the variances of the Lorentzian and Gaussian distributions expressed in the approximant.