Efeitos isotópicos em espectroscopia rotacional molecular com vistas a aplicações em radioastronomia

Abstract

In this thesis we report a theoretical and computational study of the isotope effect in molecular rotational spectroscopy for various isotopologues systems. For this study, we used a adiabatic variational correction, which has the ability to compute the effects of finite nuclear mass, together with a perturbation method which takes into account the effects of anharmonic force field, and vibrational averaging. This methodology is able to calculate with good accuracy relative to experimental data the dipole moments for a considerable range of diatomic and polyatomic molecule. We apply the same calculation of the dipole moments of various systems polyatomic isotopologues of astrophysical interest. Then we calculated the rotational constants for these systems and employ techniques to simulate the pure rotational spectra of some of these systems. This type of study has been done for some typical temperatures of interstellar and circumstellar media with a view to the use of synthetic spectra to assist possible detections of isotopologues by radio astronomy.