A manuscript reporting more extensive calculations to temperatures of 140 K is in press in the Ap. The manuscript is available here as a PostScript file or tex file. More extensive molecular scattering calculations with the same potential energy surface were subsequently done by these authors, Ap. These calculations were significantly extended by S. Green, Ap. He was used with essentially exact coupled channel molecular scattering calculations to obtain rates among the lowest 8 levels for temperatures of 5 - 100 K. Results were published in S. Green and P. Thaddeus, Ap.
More recent observations require rates for higher rotational levels and higher temperatures.
In order to interpret more recent observations of higher rotational levels in warmer sources, these calculations have been extended as described by B.E. Turner, K.-W. Chan, S. Green, and D.A. Lubowich, Ap. Understanding of this phenomenon requires knowledge of collision rates and, in particular, the relative rates for vibrational and pure rotational excitation at temperatures of a few thousand kelvin. These rates were obtained by R.J. Bieniek and S. Green, Ap. SiO is also observed in lower temperature interstellar gas. The earlier potential of Bieniek and Green was refitted to give a representation more appropriate for low energy rotational excitation and collision dynamics were treated within the coupled states approximation as described in B.E. Turner, K.-W. Chan, S. Green, and D.A. Lubowich, Ap.