  We perform the first statistical study of the effects of the interaction of
suprathermal electrons with narrow-band whistler mode waves in the solar wind.
We show that this interaction does occur and that it is associated with
enhanced widths of the so called strahl component. The latter is directed along
the inter- planetary magnetic field away from the Sun. We do the study by
comparing the strahl pitch angle widths in the solar wind at 1AU in the absence
of large scale discontinuities and transient structures, such as interplanetary
shocks, interplanetary coronal mass ejections, stream interaction regions, etc.
during times when the whistler mode waves were present and when they were
absent. This is done by using the data from two Cluster instruments: STAFF data
in frequency range between ~0.1 Hz and ~200 Hz were used for determining the
wave properties and PEACE datasets at twelve central energies between ~57 eV
(equivalent to ~10 typical electron thermal energies in the solar wind, E_T )
and ~676 eV (~113 E_T ) for pitch angle measurements. Statistical analysis
shows that during the inter- vals with the whistler waves the strahl component
on average exhibits pitch angle widths between 2 and 12 degrees larger than
during the intervals when these waves are not present. The largest difference
is obtained for the electron central energy of ~344 eV (~57 E_T ).
