The rotational excitation of OCS by He at low temperatures

Cross-sections and rate coefficients have been calculated for the excitatio n of rotational levels J less than or equal to 29 of OCS by He at low tempe ratures (T less than or equal to 150 K). The quantum mechanical coupled cha nnels method was used, without significant approximations other than the fi nite size of the basis set. The results are compared with those calculated by Green & Chapman for the excitation of OCS by para-H-2 (J = 0).