Has any verification of the presence (other than volume) of the mon- atomic Hydrogen and Oxygen atoms been done?

A. Not enough, we’re working on that. See our current theories:
https://www.eagle-research.com/browngas/whatisbg/watergas.php https://www.eagle-research.com/browngas/whatisbg/whatis.php
Another example of this ‘cold’ type of monatomic flame was reported years ago: -Popular Science May 1950, page 155; “‘Hot Torch Has “Cold” Flame’: A torch so hot it melts Tungsten or quartz-yet has a “cold” flame- has been invented by Dr. J. D. Cobine….a magnetron tube….make the molecules in a nitrogen gas jet break up into atoms. When the nitrogen atoms hit a surface, they join up into molecules again, liberating a great deal of heat. However, the heat exists only at the surface of the work, so the flame itself is not hot in the ordinary sense….”