Daniel Halwidl presents the development of an effusive molecular beam apparatus which allows
the dosing of gases liquids and solids in ultra-high vacuum. The apparatus is designed to
adsorb precise and reproducible doses to a defined area on metal oxide samples which is
required in Temperature Programmed Desorption and other surface chemistry experiments. The
design and the construction of the apparatus is described. The properties of the molecular beam
are experimentally confirmed. The beam profile has a core diameter of 3.5 mm and a standard
core pressure of 4 x 10-8 mbar while the background pressure is 4 orders of magnitude lower.
