We have calculated the ripplon-limited mobility of electrons localized
over the He-3-He-4 solution, whose surface contains a thin film enric
hed with He-3, by taking into account viscous damping in the evaluatio
n of the dispersion relation of interfacial modes. We have considered
the electron-ripplon scattering from the low-damped capillary-like mod
e, which is similar to that of ripplons in uniform liquid. The tempera
ture dependence of the electron mobility is shown for some values of t
he film thickness. The mobility is also calculated for electrons over
pure bulk 3He and an excellent agreement is found with the experimenta
l results. (C) 1998 Elsevier Science B.V. All rights reserved.