Brown dwarfs in the Pleiades and the initial mass function across the stellar/substellar boundary

We present a new sample of brown dwarf (BD) candidates from a survey coveri ng 6 degrees x 6 degrees centred on the Pleiades. The survey was constructe d using I- and R-band photographic plates, from the United Kingdom Schmidt Telescope, measured using the new high-precision microdensitometer SuperCOS MOS at the Royal Observatory, Edinburgh. Objects as faint as or up to simil ar to 0.5 mag fainter than the Pleiades lithium boundary are selected on th e basis of having extremely red photographic colours and proper motions con sistent with cluster membership; follow-up near-infrared and infrared photo electric photometry yields nine candidate ED Pleiads. Coordinates, magnitud es and finders are presented for these objects. We use these data and infor mation on higher mass stars to construct a mass function having an increasi ngly shallow gradient towards and across the stellar/substellar boundary; a few of the candidates are found at distances of more than 2 degrees from t he nominal cluster centre. We discuss the implications of these results for future surveys.