  We present electron energy-loss spectroscopic measurements of potassium (K)
intercalated tungsten diselenide (WSe2). After exposure of pristine WSe2 films
to potassium, we observe a charge carrier plasmon excitation at about 0.97 eV,
which indicates a semiconductor to metal transition. Our data signal the
formation of one particular doped K-WSe2 phase. A Kramers-Kronig analysis (KKA)
allows the determination of the dielectric function and to estimate the
composition of about K0.6WSe2. Momentum dependent measurements reveal a
substantial plasmon dispersion to higher energies.
