Abstract:
The first microwave measurements of an electronically excited molecular species in the Earth's atmosphere are presented. Local thermodynamic equilibrium (LTE) rotational line emission from mesopheric O<sub>2</sub> (<sup>1</sup>delta-<sub>g</sub>) was observed at a frequency of 255.01794 GHz (Lambda approx. 1.2mm), employing the National Radio Astronomy Observatory (NRAO) millimeter facility at Kitt Peak, Arizona (32°N, 111°W).