Abstract
An analysis of rocket AMF‐VB‐41 measurements of the spatial variation of the I6300/I5200 intensity ratio in the dayside cleft and polar cap ionosphere is reported. The measured variation of the I6300/I5200 ratio is not consistent with significant production of 6300 Å emission via the reaction N(²D) + O2 → NO + O(¹D). An upper limit to the O(¹D) yield of 0.1 is obtained for this mechanism.