2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/124370It is shown how S-matrix theory and the concept of continuous quantum measurements can be combined to yield Markovian master equations which describe the environmental interaction non-perturbatively. The method is then applied to obtain the master equation for the effects of a gas on the internal dynamics of an immobile complex quantum system, such as a trapped molecule, in terms of the exact multi-channel scattering amplitudes.5 pages; published versionQuantum Physicstext