A MONTE-CARLO MODEL OF THE ROTATION OF A BIG, ISOLATED MOLECULE IN THE ISM

In the diffuse interstellar medium a molecule experiences isolation co nditions that cannot (yet?) be achieved in the laboratory. In such con ditions its rotation is dominated by the interaction with the radiatio n field through a complex statistical equilibrium. This problem has be en analyzed numerically with MonteCarlo techniques, for a simplified P AH molecule model. As a possible application, the result has been used to calculate rotational profiles of absorption bands, suitable for di rect comparison with observed molecular bands profiles.