Abstract
We report the first measurements of microwave excitation and ionization of excited hydrogen atoms for scaled frequencies up to 2.8. Classical 3D calculations which directly model this 36.021-GHz experiment agree quite well for , agree less well for , and do not agree for . This supports theoretical predictions that as rises above 1, quantal ionization threshold fields rise above those for the onset of classical chaos; however, the data continue to reveal local stability near certain rational frequency ratios that recalls classical behavior.
- Received 18 August 1988
DOI:https://doi.org/10.1103/PhysRevLett.61.2011
©1988 American Physical Society