Atomic Physics Seminars

Atomic
Monday, April 1, 2013
3:30 PM
Physics Building, Room 204
Note special time.

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"Metastable states in microwave ionization"


Alexandr Arakelyan , University of Virginia
[Host: Tom Gallagher]
ABSTRACT:
We report the excitation of metastable Li Rydberg atoms in the presence of a strong 38.3 GHz microwave field. We detect approximately 5% of the initial population in very high Rydberg states with n > 215 after the microwave pulse for a wide range of initial binding energies. The surviving population of atoms displays a periodic comb structure in energy with a periodicity matching the structure of the 38.3 GHz microwave field. A small static field displaces the entire comb to lower energy, and the high lying states disappear when the static field exceeds 30 mV/cm. We also perform measurements of microwave ionization thresholds in Li and, in spite of the fact that the pulse is 8000 cycles long, detect approximately 5% of the initial population in extremely high-lying states when the microwave pulse is subsequent to the laser excitation of a Rydberg state of any binding energy. We suggest that these atoms are trapped in metastable atom-field states during the microwave pulse and relax to the high-lying states when the field is turned off.
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