Diagrammatical analysis of laser-switched collision processes

We have used a diagrammatic approach first developed for nonlinear optical calculations of the density operator to obtain expressions for the transition probability in various laser-switched collision processes. Not only do these diagrams considerably simplify the algebra involved in such calculations, but they also afford a clear visualization of the interaction. In particular, pair absorption, laser-switched Raman scattering, and collisionally enhanced hot luminescence and four-wave mixing processes are considered.