DIFFERENCES IN THE DETACHMENT OF ELECTRON BUBBLES FROM SUPERFLUID HE-4 DROPLETS VERSUS NONSUPERFLUID HE-3 DROPLETS

The rate of detachment of electron bubbles inside size-selected He-4 a nd He-3 droplets (10(5)-10(7) atoms) has been measured. At zero electr ic field the lifetimes of 4He droplets increase with size from 10(-3) to 0.2 s, orders of magnitude smaller than previously predicted. With increasing fields the detachment gradually increases for 4He droplets, whereas a sharp threshold was found at 1.45 kV/cm for He-3 droplets, independent of size. A simple dynamical model which accounts for super fluidity in the 4He droplets versus a viscous dynamics in He-3 can exp lain the observations. [S0031-9007(98)07487-0].