  The chemical content of the planetary nebula NGC 3918 is investigated through
deep, high-resolution (R~40000) UVES at VLT spectrophotometric data. We
identify and measure more than 750 emission lines, making ours one of the
deepest spectra ever taken for a planetary nebula. Among these lines we detect
very faint lines of several neutron-capture elements (Se, Kr, Rb, and Xe),
which enable us to compute their chemical abundances with unprecedented
accuracy, thus constraining the efficiency of the s-process and convective
dredge-up in the progenitor star of NGC 3918.
