Inelastic collisions in para-H2:: Translation-rotation state-to-state rate coefficients and cross sections at low temperature and energy -: art. no. 064313

We report an experimental determination of the k(00) --> (02) rate coefficient for inelastic H-2 : H-2 collisions in the temperature range from 2 to 110 K based on Raman spectroscopy data in supersonic expansions of para-H-2. For this purpose a more accurate method for inverting the master equation of rotational populations is presented. The procedure permits us to reduce the measured k(00) --> (02) rate coefficient to the corresponding sigma(00) --> (02) cross section in the range of precollisional energy from 360 to 600 cm(-1). Numerical calculations of sigma(00) --> (02) carried out in the frame of the coupled channel method are also reported for different intermolecular potentials of H-2. A good agreement is found between the experimental cross section and the numerical one derived from Diep and Johnson's potential [J. Chem. Phys. 112, 4465 (2000)]. (C) 2005 American Institute of Physics.