A simple means for reproducibly dosing low vapor pressure and/or reactive gases to surfaces in ultrahigh vacuum

Adsorbate gases which are very reactive with chamber walls or which have low vapor pressures present serious difficulties in attaining precisely reproducible exposures in surface science experiments, especially if the desired exposures are small. Design considerations and details are described for an inexpensive gas dosing system which is excellently suited for precisely reproducing exposures of low vapor pressure and/or reactive gases to surfaces in UHV. Also presented is a method for calibrating the doser, such that even tiny exposures can be very accurately determined and reproduced.