  The adsorption of carbon-conjugated molecules represents an established route
to tune the electronic and optical properties of transition metal
dichalcogenide (TMDC) monolayers. Here, we demonstrate from first principles
that such a functionalization with prototypical compounds pyrene and tetracene
can also enhance the magnitude of selected plasmon resonances in a MoS$_2$
single sheet, without significantly altering their energy and dispersion. Our
proof-of-principle results indicate that such a magnification can be achieved
by proper alignment of the molecules with respect to the direction of the
transferred momentum. The distinct signatures in the loss function of the
interface compared to those of its constituents suggest not only the presence
of non-negligible interactions between them but also the possibility of using
electron energy loss spectroscopy to detect the presence and the orientation of
molecular adsorbates on TMDCs.
