  Using ab initio calculations we predict the existence of one-dimensional
(1D), atomically confined plasmons at the edges of a zigzag MoS2 nanoribbon.
The strongest plasmon originates from a metallic edge state localized on the
sulfur dimers decorating the Mo edge of the ribbon. A detailed analysis of the
dielectric function reveals that the observed deviations from the ideal 1D
plasmon behavior result from single-particle transitions between the metallic
edge state and the valence and conduction bands of the MoS2 sheet. The Mo and S
edges of the ribbon are clearly distinguishable in calculated spatially
resolved electron energy loss spectrum owing to the different plasmonic
properties of the two edges. The edge plasmons could potentially be utilized
for tuning the photocatalytic activity of MoS2 nanoparticles.
