  Gravitationally lensed systems allow a detailed view of galaxies at high
redshift. High spatial- and spectral-resolution measurements of arc-like
structures can offer unique constraints on the physical and dynamical
properties of high-z systems. We present near-infrared spectra centred on the
gravitational arcs of six known z ~ 2 lensed star-forming galaxies of stellar
masses of 10^9-10^11 Msun and star formation rate (SFR) in the range between 10
and 400 Msun/yr. Ground layer adaptive optics (AO)-assisted observations are
obtained at the Large Binocular Telescope (LBT) with the LUCI spectrographs
during the commissioning of the ARGOS facility. We used MOS masks with curved
slits to follow the extended arched structures and study the diagnostic
emission lines. Combining spatially resolved kinematic properties across the
arc-like morphologies, emission line diagnostics and archival information, we
distinguish between merging and rotationally supported systems, and reveal the
possible presence of ejected gas. For galaxies that have evidence for outflows,
we derive outflow energetics and mass-loading factors compatible with those
observed for stellar winds in local and high-z galaxies. We also use flux ratio
diagnostics to derive gas-phase metallicities. The low signal-to-noise ratio in
the faint H$\beta$ and nitrogen lines allows us to derive an upper limit of ~
0.15 dex for the spatial variations in metallicity along the slit for the
lensed galaxy J1038. Analysed near-infrared spectra presented here represent
the first scientific demonstration of performing AO-assisted multi-object
spectroscopy with narrow curved-shape slits. The increased angular and spectral
resolution, combined with the binocular operation mode with the 8.4-m-wide eyes
of LBT, will allow the characterisation of kinematic and chemical properties of
a large sample of galaxies at high-z in the near future.
