Pure rotational Q-branch spectrum of silane- 28Si in the vibrational ground state observed by microwave Fourier transform spectroscopy
A pulsed microwave Fourier transform (MWFT) spectrometer operating in the 8- to 18-GHz frequency range has been used to observe pure rotational Q-branch microwave transitions of silane- 28Si. The 49 measured transitions are of all three parity-allowed types A1- A2, E- E, and F1- F2, and cover the range 13 ≤ J ≤ 25. A set of refined tensorial centrifugal distortion constants DT, H4T, H6T, L4T, L6T, and L8T has been determined by a least-squares fit from a total of 70 measurements. The fit included the 49 MWFT measurements of this work, 11 transitions observed with Stark spectroscopy, nine infrared-radio frequency double-resonance measurements, and one zero-field splitting determined from an avoided-crossing molecular-beam experiment.