Raman Spectroscopic Experiments on Boltzmann Collision Integral in Supersonic Jets

9 pages, 16 figures.-- PACS nrs.: 33.20.Fb, 47.40.Ki, 51.10.+y, 47.40.Nm, 34.50.Ez, 64.60.Qb.State of the art Raman spectroscopy adapted to quantitative investigation of gasdynamic problems in supersonic jets is reported. The facilities employed in these experiments are based on high spatial resolution (<5 µm) and high sensitivity spectroscopy (<1 photon/sec), providing us with absolute number density and rotational population data of unprecedented accuracy in wide range of conditions. Data from the zone of silence of the jet are combined with the state-to-state colisional rates in the frame of a master equation derived from Boltzmann collision integral, leading to a detail understanding of the underlying physics of relaxation, and of nucleation kinetics in terms of the most elementary collision processes.This research has been supported by the Spanish Ministerio de Educación y Ciencia, Projects PB97-1203, BFM2001-2276, FIS2004-02576, HF2004-232, ESP2004-21060, and Madrid ASTROCAM network.Peer reviewe