Predictions on Finding the SiH+ and SiH in Interstellar Space

Frequencies are computed for transitions in the SiH⁺ and SiH molecules which are expected to occur in the millimeter region usually covered by radiowave astronomy. These molecules are expected to be in low-temperature sources whose state temperatures are not greater than about 20 K. On the basis of binary gas-phase reactions, the formation and destruction of the SiH⁺ and the SiH radicals are also discussed.