  The femtosecond response of NO-doped rare gas matrices is studied within a
stochastic Langevin theoretical framework. As is shown, a simple damped
harmonic oscillator model can describe properly the absorption and emission
line shapes associated with the NO ($A^2\Sigma^+ \longleftrightarrow X^2\Pi$)
electronic transitions inside these media as well as the matrix first-solvation
shell response in a process with two timescales, finding a fairly good
agreement with available experimental data. This approach thus constitutes an
alternative and complementary way to analyze the structural relaxation dynamics
of systems in liquids and solids, leading to a better understanding of the
underlying physics.
