Einstein Frequency Measurement for a Strongly Coupled Dusty Plasma

The Einstein frequency Omega(E) was experimentally determined for a 2-D dusty plasma. We found Omega(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 omega(pd), we found the ratio Omega(E)/omega(pd) approximate to 1/root 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.