  We consider the evaporation of a thin liquid layer which consists of a binary
mixture of volatile liquids. The mixture is on top of a heated substrate and in
contact with the gas phase that consists of the same vapour as the binary
mixture. The effect of thermocapillarity, solutocapillarity and the van der
Waals interactions are considered. We derive the long-wave evolution equations
for the free interface and the volume fraction that govern the two-dimensional
stability of the layer subject to the above coupled mechanisms and perform a
linear stability analysis. Our results demonstrate two modes of instabilities,
a monotonic instability mode and an oscillatory instability mode. We supplement
our results from stability analysis with transient simulations to examine the
dynamics in the nonlinear regime and analyse how these instabilities evolve
with time. More precisely we discuss how the effect of relative volatility
along with the competition between thermal and solutal Marangoni effect defines
the mode of instability that develops during the evaporation of the liquid
layer due to preferential evaporation of one of the components.
