Search for Lambda-Doubling Transitions of SiH in Orion KL

A recent submillimeter line survey of Orion KL claimed detection of SiH. This paper reports on GBT observations of the 5.7 GHz Lambda-doubling transitions of SiH in Orion. Many recombination lines, including C164-delta, are seen, but SiH is not detected. The nondetection corresponds to an upper limit of 1.5 x 10^15 cm^-2 (4 sigma) for the beam-averaged column density of SiH. This suggests that the fractional abundance of SiH in the extended ridge is no more than twice that in the hot core.