Experimental and theoretical photochemistry: application to the cometary environment and Titan’s atmosphere

Coupling the data obtained from laboratory experiments, theoretical modelling and observation is the way to reach a better understanding of the organic chemistry involved in a planetary or a cometary atmosphere. We discuss briefly here the different interactions between experimental studies and observations and develop the contribution of laboratory experiments to models in the case of both Titan and cometary investigations. ticular, we point out the lack of fundamental data such as kinetic rate constants and quantum yields necessary to build theoretical models. We present a photochemical experiment dedicated to provide such parameters in order to support the theoretical modelling of interactions between the cometary nucleus and the coma. cuss the limitations of simulation experiments with respect to extracting useful data for modelling. We propose that the comparison of simpler, well-constrained laboratory experiments and theoretical models of these systems can lead to a critical examination of the accuracy of the model’s chemical schemes. We illustrate this for the case of Titan. studies have direct implications for the preparation and the analysis of results from planetary space missions.