  In spite of large overabundances of Xe II observed in numerous
mercury-manganese (HgMn) stars, Xe II oscillator strengths are only available
for a very limited number of transitions. As a consequence, several
unidentified lines in the spectra of HgMn stars could be due to Xe II. In
addition, some predicted Xe II lines are redshifted by about 0.1 A from stellar
unidentified lines, raising the question about the wavelength accuracy of the
Xe II line data available in the literature. For these reasons we investigated
the Xe II lines lying in the 3900-4521 A, 4769-7542 A, and 7660-8000 A spectral
ranges of four well-studied HgMn stars. We compared the Xe II wavelengths
listed in the NIST database with the position of the lines observed in the
high-resolution UVES spectrum of the xenon-overabundant, slowly rotating HgMn
stars HR 6000, and we modified them when needed. We derived astrophysical
oscillator strengths for all the Xe II observed lines and compared them with
the literature values, when available. In this framework, we performed a
complete abundance analysis of HD 71066, while we relied on our previous works
for the other stars. We find that all the lines with wavelengths related to the
6d and 7s energy levels have a corresponding unidentified spectral line,
blueshifted by the same quantity of about 0.1 A in all the four stars, so that
we identified these lines as coming from Xe II and modified their NIST
wavelength value according to the observed stellar value. We find that the Xe
II stellar oscillator strengths may differ from one star to another from 0.0
dex to 0.3 dex. We adopted the average of the oscillator strengths derived from
the four stars as final astrophysical oscillator strength.
