  We investigate the cause of the suppressed Balmer series and the origin of
the white-light continuum emission in the X1.0 class solar flare on 2014 June
11. We use radiative hydrodynamic simulations to model the response of the
flaring atmosphere to both electron and proton beams which are energetically
constrained using RHESSI and Fermi observations. A comparison of synthetic
spectra with the observations allow us to narrow the range of beam fluxes and
low energy cut-off that may be applicable to this event. We conclude that the
electron and proton beams that can reproduce the observed spectral features are
those that have relatively low fluxes and high values for the low energy
cut-off. While electron beams shift the upper chromosphere and transition
region to greater geometrical heights, proton beams with a similar flux leave
these areas of the atmosphere relatively undisturbed. It is easier for proton
beams to penetrate to the deeper layers and not deposit their energy in the
upper chromosphere where the Balmer lines are formed. The relatively weak
particle beams that are applicable to this flare do not cause a significant
shift of the $\tau=1$ surface and the observed excess WL emission is optically
thin.
