  A new type of quasi-two-dimensional complex plasma system was observed which
consisted of monodisperse microspheres and their binary agglomerations
(dimers). The particles and their dimers levitated in a plasma sheath at
slightly different heights and formed two distinct sublayers. The sys- tem did
not crystallize and may be characterized as disordered solid. The dimers were
identified based on their characteristic appearance in defocused images, i.e.,
rotating interference fringe pat- terns. The in-plane and inter-plane particle
separations exhibit nonmonotonic dependence on the discharge pressure which
agrees well with theoretical predictions.
