Einstein Frequency Measurement for a Strongly Coupled Dusty Plasma

The Einstein frequency Ω
_E
was experimentally determined for a 2-D dusty plasma. We found Ω
_E
= 49.4 s
^-1
and 50.2 s
^-1
for the collection of microspheres in a crystalline and liquid-like state, respectively. Comparing to the nominal 2-D dust plasma frequency ω
_pd
, we found the ratio Ω
_E
/ω
_pd
≈ 1/√3. This experimental ratio is consistent with previous predictions of Yukawa simulations. Our results were obtained by analyzing images of the microspheres to obtain their positions, charge, and the screening length; we used these measurements to calculate resonant frequencies of test particles.