  Dimers and trimers of carbonyl sulfide (OCS) molecules embedded in helium
nanodroplets are aligned by a linearly polarized 160 ps long moderately intense
laser pulse and Coulomb exploded with an intense 40 fs long probe pulse in
order to determine their structures. For the dimer, recording of 2D images of
OCS$^+$ and S$^+$ ions and covariance analysis of the emission directions of
the ions allow us to conclude that the structure is a slipped-parallel shape
similar to the structure found for gas phase dimers. For the trimer, the
OCS$^+$ ion images and corresponding covariance maps reveal the presence of a
barrel-shaped structure (as in gas phase) but also other structures not present
in the gas phase, most notably a linear chain structure.
