Abstract

Physica B 284 158-9 (2000).

Monolayers of ³He on the Surface of Bulk Superfluid ⁴He

J.P. Warren and C.D.H. Williams

School of Physics, University of Exeter, Exeter, EX4 4QL (UK).

(Submitted 17 June 1999)

We have used quantum evaporation to investigate the two-dimensional fermion system that forms at the free surface of (initially isotopically pure) ⁴He when small quantities of ³He are added to it. By measuring the first-arrival times of the evaporated atoms, we have determined that the ³He--³He potential in this system is V_3S/k_B=0.23±0.02 K nm² (repulsive) and estimated a value ofm_3S=(1.53±0.02)m₃ for the zero-coverage effective mass. We have also observed the predicted second layer-state which becomes occupied once the first layer-state density exceeds about 0.6 monolayers.

Keywords: liquid helium, surfaces, quantum evaporation, 2-D fermion systems.
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