Collisional rates for vibrational-rotational transitions in circumstellar SiO masers

Calculations for rotational population inversion in circumstellar SiO masers require collisional rates for vibrational-rotational transitions. This Letter reports quantum mechanical, state-to-state collisional rate coefficients for pure rotational and vibrational-rotational transitions among the first three vibrational stages of SiO. These are expressed in terms of simple two-parameter power-law fits accurate in the temperature range 1000-3000K.