DETECTION OF SiOH (X2A') BY FOURIER TRANSFORM MICROWAVE SPECTROSCOPY

The rotational spectrum of the free radical SiOH in its ground electronic state has been observed by Fourier transform microwave spectroscopy. The transition has been detected for the main species SiOH and for the rare isotopic species SiOH, Si OH, and SiOD. The same transition has also been observed in the excited vibrational states $ and $ for the most abundant species. From this data, precise spectroscopic constants have been derived for this plausible astronomical molecule, as has an experimental structure (" ). In addition, the transition of HNSi has been detected at high spectral resolution by the same technique, yielding a precise value for the nitrogen quadrupole coupling constant.