Abstract: Evaporation cell for a liquid compound suitable for molecular jet epitaxy on a substrate from a compound which is liquid at ambient temperature and which comprises in per se known manner a cell containing said liquid compound in a main ultravacuum enclosure, the cell being provided with heating means. It comprises a preliminary vacuum enclosure tightly connected to the main enclosure and having a first opening provided with a valve and a pipe for forming and regulating the preliminary vacuum in the preliminary vacuum enclosure, an upwardly oriented second opening linked with a chamber containing a large free surface area reservoir for receiving a liquid compound stock, as well as a third downwardly oriented opening linked with a disassemblable reservoir for emptying the liquid compound, while in the preliminary vacuum enclosure is provided a three-way cock connecting the cell containing the liquid compound either to the large surface reservoir, or to the disassemblable reservoir.