New Method for the Observation of Hyperfine Structure of NH3 in a ``Maser'' Oscillator

Weak hyperfine satellites have been observed with very large signal-to-noise ratios when microwave power at frequencies corresponding to these satellites is introduced into a ``maser'' which is oscillating at the frequency of the main inversion line of NH3. The satellite transitions are accompanied by a reduction of the amplitude of oscillation at the main-line frequency. A composite oscilloscope trace showing the structure of the weakest of the four quadrupole satellites associated with the 3–3 inversion line of N14H3 is presented.