  In recent years, much research has been undertaken to investigate the
suitability of two-dimensional materials to act as single-photon sources with
high optical and quantum optical quality. Amongst them, transition-metal
dichalcogenides, especially WSe$_{2}$, have been one of the subjects of
intensive studies. Yet, their single-photon purity and photon
indistinguishability, remain the most significant challenges to compete with
mature semiconducting systems such as self-assembled InGaAs quantum dots. In
this work, we explore the emission properties of quantum emitters in a
WSe$_{2}$ monolayer which are induced by metallic nanoparticles. Under
quasi-resonant pulsed excitation, we verify clean single-photon emission with a
$g^{(2)}(0) = 0.036\pm0.004$. Furthermore, we determine its temperature
dependent coherence time via Michelson interferometry, where a value of
(13.5$\pm$1.0) ps is extracted for the zero-phonon line (ZPL) at 4 K, which
reduces to (9$\pm$2) ps at 8 K. Associated time-resolved photoluminescence
experiments reveal a decrease of the decay time from (2.4$\pm$0.1) ns to
(0.42$\pm$0.05) ns. This change in decay time is explained by a model which
considers a F\"orster-type resonant energy transfer process, which yields a
strong temperature induced energy loss from the SPE to the nearby Ag
nanoparticle.
