  We present echelle spectrophotometry of the Galactic H II region S 311. The
data have been taken with the Very Large Telescope UVES echelle spectrograph in
the 3100 to 10400 angstroms range. We have measured the intensities of 263
emission lines, 178 are permitted lines of H0, D0 (deuterium), He0, C0, C+, N0,
N+, O0, O+, S+, Si0, Si+, Ar0 and Fe0; some of them are produced by
recombination and others mainly by fluorescence. Physical conditions have been
derived using different continuum and line intensity ratios. We have derived
He+, C++ and O++ ionic abundances from pure recombination lines as well as
abundances from collisionally excited lines for a large number of ions of
different elements. We have obtained consistent estimations of t2 applying
different methods. We have found that the temperature fluctuations paradigm is
consistent with the t2(He I) vs. t2(H I) relation for H II regions, in contrast
with what has been found for planetary nebulae. We report the detection of
deuterium Balmer lines up to D6 in the blue wings of the hydrogen lines, which
excitation mechanism seems to be continuum fluorescence.
