  We analyze the experimental data on inelastic neutron scattering by a thin
~5-atomic-layer film of liquid helium at three different temperatures: T=0.4K,
0.98K and 1.3K. These data were partially published previously, but here we
present them in a better quality and at various temperatures. The neutron
scattering intensity plots, in addition to the previously know dispersion of
phonons and ripplons, suggest a branch of gapped surface excitations with
activation energy $\sim 4.5$K and the dispersion similar to that expected for
surfons - the bound quantum states of helium atoms above liquid helium surface,
proposed and investigated theoretically. These data, probably, provide the
first direct experimental confirmation of surfons. Before these surface
excitations received only indirect experimental substantiation, based on the
temperature dependence of surface tension coefficient and on their interaction
with surface electrons. The existence of surfons as an additional type of
surface excitations, although being debated yet, is very important for various
physical properties of He surface. We also analyze previous numerical results
on excitations in liquid helium and argue that surface excitations similar to
surfons have been previously obtained by numerical calculations and called
resonance interface states.
